sparc32: genirq support

The conversion of sparc32 to genirq is based on original work done
by David S. Miller.
Daniel Hellstrom has helped in the conversion and implemented
the shutdowm functionality.
Marcel van Nies <morcles@gmail.com> has tested this on Sparc Station 20

Test status:
sun4c      - not tested
sun4m,pci  - not tested
sun4m,sbus - tested (Sparc Classic, Sparc Station 5, Sparc Station 20)
sun4d      - not tested
leon       - tested on various combinations of leon boards,
             including SMP variants

generic
   Introduce use of GENERIC_HARDIRQS and GENERIC_IRQ_SHOW
   Allocate 64 IRQs - which is enough even for SS2000
   Use a table of irq_bucket to maintain uses IRQs
      irq_bucket is also used to chain several irq's that
      must be called when the same intrrupt is asserted
   Use irq_link to link a interrupt source to the irq
   All plafforms must now supply their own build_device_irq method
   handler_irq rewriten to use generic irq support

floppy
   Read FLOPPY_IRQ from platform device
   Use generic request_irq to register the floppy interrupt
   Rewrote sparc_floppy_irq to use the generic irq support

pcic:
   Introduce irq_chip
   Store mask in chip_data for use in mask/unmask functions
   Add build_device_irq for pcic
   Use pcic_build_device_irq in pci_time_init
   allocate virtual irqs in pcic_fill_irq

sun4c:
   Introduce irq_chip
   Store mask in chip_data for use in mask/unmask functions
   Add build_device_irq for sun4c
   Use sun4c_build_device_irq in sun4c_init_timers

sun4m:
   Introduce irq_chip
   Introduce dedicated mask/unmask methods
   Introduce sun4m_handler_data that allow easy access to necessary
     data in the mask/unmask functions
   Add a helper method to enable profile_timer (used from smp)
   Added sun4m_build_device_irq
   Use sun4m_build_device_irq in sun4m_init_timers

   TODO:
      There is no replacement for smp_rotate that always scheduled
      next CPU as interrupt target upon an interrupt

sun4d:
   Introduce irq_chip
   Introduce dedicated mask/unmask methods
   Introduce sun4d_handler_data that allow easy access to
   necessary data in mask/unmask fuctions
   Rewrote sun4d_handler_irq to use generic irq support

   TODO:
      The original implmentation of enable/disable had:

          if (irq < NR_IRQS)
               return;

      The new implmentation does not distingush between SBUS and cpu
      interrupts.
      I am no sure what is right here. I assume we need to do
      something for the cpu interrupts.

      I have not succeeded booting my sun4d box (with or without this patch)
      and my understanding of this platfrom is limited.
      So I would be a bit suprised if this works.

leon:
   Introduce irq_chip
   Store mask in chip_data for use in mask/unmask functions
   Add build_device_irq for leon
   Use leon_build_device_irq in leon_init_timers

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Daniel Hellstrom <daniel@gaisler.com>
Tested-by: Daniel Hellstrom <daniel@gaisler.com>
Tested-by: Marcel van Nies <morcles@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>