ARM: dts: dra76-evm: Add pinctrl data for higher speed MMC/SD modes

The SD card interface on DRA76x EVM can support
high speed SD cards. The eMMC onboard can support
upto HS200 mode.

Enable support for these higher speed modes in the
device-tree file.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>