arm64: dts: allwinner: a100: set maximum MMC frequency

arm64: dts: allwinner: a100: set maximum MMC frequency

The manual for the Allwinner A133 SoC mentions that the maximum
supported MMC frequency is 150 MHz, for all of the MMC devices.

Describe that in the DT entry, to help drivers setting the right
interface frequency.

Fixes: fcfbb8d9ec58 ("arm64: allwinner: a100: Add MMC related nodes")
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Link: https://patch.msgid.link/20250505202416.23753-1-andre.przywara@arm.com
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
[ upstream commit: d8f10550448b03d3c5c6d9392119205c65ebfc89 ]

(cherry picked from commit 85e37e6a8a002eb231df8209478d7ff2b134a451)