For we don't know mmc bus width from reading registers, the only way
to check is to test.

Current compare offset is:
EXT_CSD_PARTITIONING_SUPPORT
EXT_CSD_ERASE_GROUP_DEF
EXT_CSD_REV
EXT_CSD_HC_ERASE_GRP_SIZE
EXT_CSD_SEC_CNT
Signed-off-by: NLei Wen <leiwen@marvell.com>