ARM: dts: keystone-k2g-evm: Use sdhci-omap programming model

Use sdhci-omap programming model based on the generic sdhci
library for programming the MMC/SD controller.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>