ARM: DTS: k2g-evm: Enable UART2 for communication to BMC

K2G GP EVM has a Baseboard Management Controller (BMC) on board.
This controller handles things like setting the SoCs boot mode along
with controlling the on board character LCD display module.

Enable support for UART2 which helps communication with BMC. This
enables userspace applications to display something on the LCD
controlled by the BMC, for example.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>