sh: kgdb section mismatches and tidying.

The kgdb console setup was callable from a left-over deferred
initialization path, which in turn depends on __init symbols. Since
the deferred initialization was removed some time ago, kill off the
rest of those remnants and move kgdb_init() and friends to __init.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>