drivers/memstick/host/jmb38x_ms: 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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>