mmc: moxart: remove unneeded check for drvdata

mmc: moxart: remove unneeded check for drvdata

The 'struct mmc_host *mmc' comes from drvdata set at the end of probe,
so it cannot be NULL.  The code already dereferences it few lines before
the check with mmc_priv().  This also fixes smatch warning:

  drivers/mmc/host/moxart-mmc.c:692 moxart_remove() warn: variable dereferenced before check 'mmc' (see line 688)

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200923153739.30327-1-krzk@kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>