mmc: Use the eMMC mmcblk0 mapping
With commit https://github.com/torvalds/linux/commit/fa2d0aa96941e8dc347e49a04c75468e3002ee20 cherry-picked to our current kernel the aliasing works as it worked for previous linux ports, namely the eMMC equipped on the iMX6 Garz & Fricke boards is mapped to mmcblk0.
Thus use this mmcblk0 mapping to refer to the eMMC.
See also https://gitlab.com/garz-fricke/kernel/linux-guf/-/merge_requests/18
BCS 746-000100
Edited by Jonas Höppner