[media] drivers/media/radio/radio-maxiradio: Convert to module_pci_driver

use module_pci_driver instead of init/exit, make code clean

Signed-off-by: Libo Chen <libo.chen@huawei.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>