Make irq_*_affinity depend on CONFIG_GENERIC_HARDIRQS too.

In interrupt.h these functions are declared only if
CONFIG_GENERIC_HARDIRQS is set.  We should define them under identical
conditions.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>