Enable UART3 which is connected to 40pin header.

Enable UART3 and properly configure pinmux settings
for TX/RX pins.

Bug: 131176938, 131178416

Change-Id: I0bf5da18298d26ea5d7215d3cd581a9cc7d047a7
Signed-off-by: Leonid Lobachev <leonidl@google.com>
1 file changed