Fix some compiler warnings:

- The first two are spurious gcc warnings, but quieten them up regardless
- Add a missing include
- Use register_sysrq_key instead of __sysrq_put_key_op
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>