mwifiex: fix memory leak issue for sdio and pcie cards

When driver is failed to load, card pointer doesn't get
freed. We will free it in cleanup handler which is called
in failure as well as unload path.
Also, update drvdata in init/cleanup handlers instead of
register/unregister handlers.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>