[PATCH] IB/mthca: allocate correct number of doorbell pages

Doorbell record pages are allocated in HCA page size chunks (always 4096
bytes), so we need to divide by 4096 and not PAGE_SIZE when figuring out how
many pages we'll need space for.

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