sparc: merge header files with trivial differences

A manual inspection revealed that the following headerfiles
contained only trivial differences:
hw_irq.h idprom.h kmap_types.h kvm.h spinlock_types.h sunbpp.h unaligned.h

The only noteworthy change are that sparc64 had a volatile
qualifer that sparc missed in spinlock_types.h.

In addition a few comments were updated.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>