ARM: dts: colibri-vf: Add pinmux for UART_0 aka UART_A RTS/CTS pins

Add pinmux for UART_A RTS, CTS pin's.
Signed-off-by: NBhuvanchandra DV <bhuvanchandra.dv@toradex.com>
Acked-by: NStefan Agner <stefan@agner.ch>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/vf-colibri.dtsi

@@ -305,6 +305,8 @@ pinctrl_uart0: uart0grp {
 			fsl,pins = <
 				VF610_PAD_PTB10__UART0_TX		0x21a2
 				VF610_PAD_PTB11__UART0_RX		0x21a1
+				VF610_PAD_PTB12__UART0_RTS		0x21a2
+				VF610_PAD_PTB13__UART0_CTS		0x21a1
 			>;
 		};