RDMA/mthca: Remove unnecessary NULL assignments

There are many pointers assigned first, which need not to be initialized, so
remove the NULL assignments.

Signed-off-by: Ruan Jinjie <ruanjinjie@huawei.com>
Link: https://lore.kernel.org/r/20230731065543.2285928-1-ruanjinjie@huawei.com


Signed-off-by: Leon Romanovsky <leon@kernel.org>