mmc: sdhci: Check mrq->cmd in sdhci_tasklet_finish
mmc: sdhci: Check mrq->cmd in sdhci_tasklet_finish

It seems that under certain circumstances that the sdhci_tasklet_finish()
call can be entered with mrq->cmd set to NULL, causing the system to crash
with a NULL pointer de-reference.

Unable to handle kernel NULL pointer dereference at virtual address 00000000
PC is at sdhci_tasklet_finish+0x34/0xe8
LR is at sdhci_tasklet_finish+0x24/0xe8

Seen on S3C6410 system.

Signed-off-by: Ben Dooks <1177f64998f284a7348354b8e91cbbe575d9858a@fluff.org>
Signed-off-by: Mark Brown <b51b9a92386687a9ac927cebfa0f978adeb8cea5@opensource.wolfsonmicro.com>
Cc: <4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@kernel.org>
Signed-off-by: Chris Ball <6ca7faee6ca9a094b1ee341f11b840a5608a8746@laptop.org>

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