ARM: dts: rockchip: radxa-dalang: Update sdmmc properties

Radxa dalang carrier boards are used to mount vmarc SoM's
of rk3399pro and rk3288 to make complete SBC.

Among these combinations, card detection gpio, max-frequency
properties are used with rk3399pro SoM but not required for
rk3288 SoM based on the hardware schematics.

So, let's move these sdmmc specific properties on associate
vmarc dtsi to make common use of dalang carrier device tree file.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>