ARM: OMAP: Split plat/hardware.h, use local soc.h for omap2+

As the plat and mach includes need to disappear for single zImage work,
we need to remove plat/hardware.h.

Do this by splitting plat/hardware.h into omap1 and omap2+ specific files.

The old plat/hardware.h already has omap1 only defines, so it gets moved
to mach/hardware.h for omap1. For omap2+, we use the local soc.h
that for now just includes the related SoC headers to keep this patch more
readable.

Note that the local soc.h still includes plat/cpu.h that can be dealt
with in later patches. Let's also include plat/serial.h from common.h for
all the board-*.c files. This allows making the include files local later
on without patching these files again.

Note that only minimal changes are done in this patch for the
drivers/watchdog/omap_wdt.c driver to keep things compiling. Further
patches are needed to eventually remove cpu_is_omap usage in the drivers.

Also only minimal changes are done to sound/soc/omap/* to remove the
unneeded includes and to define OMAP44XX_MCPDM_L3_BASE locally so there's
no need to include omap44xx.h.

While at it, also sort some of the includes in the standard way.

Cc: linux-watchdog@vger.kernel.org
Cc: alsa-devel@alsa-project.org
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: Jarkko Nikula <jarkko.nikula@bitmer.com>
Cc: Liam Girdwood <lrg@ti.com>
Acked-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>