mediatek: fix UFS build failure
requested to merge mediatek/aiot/team-baylibre/trusted-firmware-a:aouledameur/mt8395-evb-ufs-build into mtk-v2.6
MT8395-evb-ufs target currently fails to build with this error:
undefined reference to mmc_current_boot_part
To fix this, define get_boot_partition_name() specific call for UFS storage build and keep mmc code intact.
Bug: AIOT-1245
Signed-off-by: Amjad Ouled-Ameur aouledameur@baylibre.com