mmc: core: add checks for pointers before driver shutdown
mmc: core: add checks for pointers before driver shutdown

Verify drv and card pointers before calling for driver shutdown.

Change-Id: I855e32f988ec1af475df6ed91f04618525e1a59f
Signed-off-by: Eugene Yasman <292844bb0e4ab817dd8c0424f47ca486dc80a866@codeaurora.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas