vfio/mlx5: Switch to use module_pci_driver() macro

Since pci provides the helper macro module_pci_driver(), we may replace
the module_init/exit with it.

Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
Reviewed-by: Yishai Hadas <yishaih@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20220922123507.11222-1-shangxiaojing@huawei.com


Signed-off-by: Alex Williamson <alex.williamson@redhat.com>