sh: trivial build cleanups.

Several errors were spotted during building for custom config (SMP
included). Although SMP still does not compile (no ipi and
__smp_call_function) and does not work, this looks a bit cleaner.
Some other errors obtained via gcc-4.1.0 build.

Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>