[SPARC64]: bp->pil can never be zero

Only pil0_dummy_bucket had a pil of zero and we just killed that
off, so we can delete all special case code that used bp->pil==0
as a way to identify a dummy bucket.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc arch/sparc64/kernel/irq.c
Simple merge