ARM: dts: at91sam9260: pullup rx on usart0

For consistency with all other serial pins, add this pullup. It also
prevents the signal from floating and so consuming a useless extra amount
of power in crowbarred state if nothing is connected to RX.
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

arch/arm/boot/dts/at91sam9260.dtsi

@@ -434,8 +434,8 @@ pinctrl_dbgu: dbgu-0 {
 				usart0 {
 					pinctrl_usart0: usart0-0 {
 						atmel,pins =
-							<AT91_PIOB 4 AT91_PERIPH_A AT91_PINCTRL_NONE	/* PB4 periph A */
-							 AT91_PIOB 5 AT91_PERIPH_A AT91_PINCTRL_NONE>;	/* PB5 periph A */
+							<AT91_PIOB 4 AT91_PERIPH_A AT91_PINCTRL_NONE
+							 AT91_PIOB 5 AT91_PERIPH_A AT91_PINCTRL_PULL_UP>;
 					};
 
 					pinctrl_usart0_rts: usart0_rts-0 {