RDMA/qib: Use the bitmap API when applicable

Using the bitmap API is less verbose than hand writing them.
It also improves the semantic.

While at it, initialize the bitmaps. It can't hurt.

Link: https://lore.kernel.org/r/33d8992586d382bec8b8efd83e4729fb7feaf89e.1656834106.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Leon Romanovsky <leon@kernel.org>