ARM: dts: stm32mp15: remove mmc alias

Remove the mmc alias no more required as the sequence number
of mmc device is used for boot_instance.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
2 files changed