data->{blocks, blocksize, flags} are all used outside of the if clause
checking whether data is not NULL.
Fix this to avoid dereferencing null pointers.

Fixes: bdcf89d274 ("mci: add Marvell Dove SDHCI driver")
Cc: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>