[PATCH] IB/mthca: Encapsulate command interface init

Encapsulate mthca command interface initialization/cleanup.

Signed-off-by: Roland Dreier <roland@topspin.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>