[PATCH] asm/softirq.h is dead

[PATCH] asm/softirq.h is dead

From: Christoph Hellwig <hch@lst.de>

Still three arches keep an unused copy around and quite a few places refer
to it in comments still.

Two of the two arches also include it in their _ksyms.c file, but given
that softirq.h only contains macros (which are in hardirq.c as well) that's
just a leftover as well.