arm64: dts: ti: k3-am65-main: Add support for sdhci1

Add support for the 2nd SDHCI controller on TI's AM654x SoCs.
Although it supports upto SDR104 (100 MBps @ 200 MHz) speed mode,
only enable support upto High Speed (25 MBps @ 50 MHz) for now.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>