ARM: dts: keystone-k2g-ice: Add DT nodes for few peripherals

Add DT nodes for QSPI, on board LEDS, MMC, I2C, PCA IO expander,
gpio-decoder and regulators on K2G ICE board.

Thanks to Franklin S Cooper Jr <fcooper@ti.com> for initial work on few
peripherals.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>