[PATCH] powerpc: moved ipic code to arch/powerpc

Moved 83xx and QUICC Engine interrupt handling code into arch/powerpc
as a precursor of getting 83xx sub-arch building in arch/powerpc.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>