[PATCH] xtensa: cleanups for errno and ipc.

I noticed this because I was doing some more ipc cleanups and I did the
original errno and ipc cleanups for other architectures, so it stuck out.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>