ARM: dts: keystone-k2g-evm: Enable MMC0 and MMC1

Enable MMC0 which is used for micro SD and MMC1 which is used for the on
board EMMC.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
[fcooper@ti.com: add mmc1, bufferclass and pullup/pulldown settings]
Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
[nsekhar@ti.com: add card detect GPIO support]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>