MMC_CMD1 command is used to check whether card is MMC type (checked if
CONFIG_MMCSD_MMCSUPPORT is enabled). This commit inserts nxsig_usleep
wait if this check fails. This is to ensure the communication recovers
from invalid response as this may take some time on some platforms (
samv7 for example). Following command for SDHC check may fail if sleep
is not used.
Signed-off-by: Michal Lenc <michallenc@seznam.cz>