alpha: fix breakage caused by df9ee292

Commit df9ee29270 made arch_local_irq_save and arch_local_irq_restore
static inline which with -Werror trips up on __set_hae() and _set_hae()
which are extern inline.  The naive solution is to make __set_hae() and
set_hae() static inline but for reasons described in commit d559d4a24a3fe
this breaks the generic kernel build.  Instead, since this is architecture
specific code, this patch hard wires in the architecture specific method
f disabling and enabling interrupts.

Tested-by: Michael Cree <mcree@orcon.net.nz>
Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Matt Turner <mattst88@gmail.com>