mmc_block: handle error from mmc_register_driver()
mmc_block: handle error from mmc_register_driver()

Check error from mmc_register_driver() and properly unwind
block device registration.

Signed-off-by: Akinobu Mita <3807cf899f217da549814bf6c330d3b6e6819ccf@gmail.com>
Signed-off-by: Pierre Ossman <8b64f2aeec7ea42cd6838e5b2901f7aa61dfa5d4@drzeus.cx>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas