sh: Convert struct ioctls to static defines.

This fixes up some compile failures for cases where we don't include
all of the headers. There's not much point in keeping the struct
references around anyways, most of the others have been converted
already.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>