IB/rxe: Use __func__ to print function's name

Its better to use __func__ to print functions name instead of writing
the name in the print statement.

Signed-off-by: Kamal Heib <kamalh@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>