sh: Remove unnecessary posix_types.h type overrides

Remove type overrides in <asm/posix_types.h> for the sh architecture
that are no longer necessary.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1328677745-20121-18-git-send-email-hpa@zytor.com
Cc: Paul Mundt <lethal@linux-sh.org>