[PATCH] ac97_codec: make bitfield unsigned

Make a 1-bit bitfield unsigned (no space for sign bit).
Removes 24 sparse warnings from this one file:
include/linux/ac97_codec.h:262:13: error: dubious one-bit signed bitfield

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>