mmc: core: Fix bit width test failing on old eMMC cards

PARTITION_SUPPORT needs to be set before doing the compare on version
number so the bit width test does not get invalid data.  Before this
patch, a Sandisk iNAND eMMC card would detect 1-bit width although
the hardware supports 4-bit.

Only affects old emmc devices - pre 4.4 devices.

Reported-by: Elad Yi <elad.yi@gmail.com>
Signed-off-by: Philip Rakity <prakity@yahoo.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Chris Ball <cjb@laptop.org>