IB/rxe: improved debug prints & code cleanup

1. Debugging qp state transitions and qp errors in loopback and
multiple QP tests is difficult without qp numbers in debug logs.
This patch adds qp number to important debug logs.

2. Instead of having rxe: prefix in few logs and not having in
few logs, using uniform module name prefix using pr_fmt macro.

3. Code cleanup for various warnings reported by checkpatch for
incomplete unsigned data type, line over 80 characters, return
statements.

Signed-off-by: Parav Pandit <pandit.parav@gmail.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>