mfd: Use devm_* APIs for mc13xxx: remove leftover kfree

commit e7c706b1 migrated the allocation
of struct mc13xxx to devm_* functions, but left a kfree(mc13xxx) in the
mc13xxx_common_init error path. Remove it to prevent memory corruption.

Signed-off-by: Andreas Pretzsch <apr@cn-eng.de>
Reviewed-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>