Fix for finding mmc devices on i.MX6Q icore boards
added in below comment
"icorem6: Fix to find MMC devices"
(sha1: a2b137b3)

which is reverted in during u-boot-imx merge
" Merge git://git.denx.de/u-boot-imx

"
(sha1: 6aee2ab6)

This patch, is recreated to fix merge conflict.

Cc: Stefano Babic <sbabic@denx.de>
Cc: Tom Rini <trini@konsulko.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>