mmc: core: Initialize mmc_blk_ioc_data

mmc: core: Initialize mmc_blk_ioc_data

Commit 4d0c8d0aef63 ("mmc: core: Use mrq.sbc in close-ended ffu") adds
flags uint to struct mmc_blk_ioc_data, but it does not get initialized for
RPMB ioctls which now fails.

Let's fix this by always initializing the struct and flags to zero.

Fixes: 4d0c8d0aef63 ("mmc: core: Use mrq.sbc in close-ended ffu")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218587
Link: https://lore.kernel.org/all/20231129092535.3278-1-avri.altman@wdc.com/
Cc: stable@vger.kernel.org
Signed-off-by: Mikko Rapeli <mikko.rapeli@linaro.org>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Link: https://lore.kernel.org/r/20240313133744.2405325-1-mikko.rapeli@linaro.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>