ARM: dts: rockchip: Use vmmc-supply from PMIC on rk3288-vyasa

rk808, SWITCH_REG1 has configured for sdmmc regulator as vcc_sd,
so use the same by renaming vcc33_sd to vcc_sd(as per schematic)
and drop explicit regulator definition from root.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>