ARM: dts: dra7x-evm: Provide NAND ready pin

On these boards NAND ready pin status is avilable over
GPMC_WAIT0 pin.

Read speed increases from 13768 KiB/ to 17246 KiB/s.
Write speed was unchanged at 7123 KiB/s.
Measured using mtd_speedtest.ko.
Signed-off-by: NRoger Quadros <rogerq@ti.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>

arch/arm/boot/dts/dra7-evm.dts

@@ -776,6 +776,7 @@
 		interrupt-parent = <&gpmc>;
 		interrupts = <0 IRQ_TYPE_NONE>, /* fifoevent */
 			     <1 IRQ_TYPE_NONE>; /* termcount */
+		rb-gpios = <&gpmc 0 GPIO_ACTIVE_HIGH>; /* gpmc_wait0 pin */
 		ti,nand-ecc-opt = "bch8";
 		ti,elm-id = <&elm>;
 		nand-bus-width = <16>;

arch/arm/boot/dts/dra72-evm.dts

@@ -503,6 +503,7 @@
 		interrupt-parent = <&gpmc>;
 		interrupts = <0 IRQ_TYPE_NONE>, /* fifoevent */
 			     <1 IRQ_TYPE_NONE>;	/* termcount */
+		rb-gpios = <&gpmc 0 GPIO_ACTIVE_HIGH>; /* gpmc_wait0 pin */
 		ti,nand-ecc-opt = "bch8";
 		ti,elm-id = <&elm>;
 		nand-bus-width = <16>;