ARM: dts: dra7: Remove redundant nand property

wait pin monitoring is not used for nand so it is pointless to
have the gpmc,wait-monitoring-ns property.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

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

@@ -770,7 +770,6 @@
 		gpmc,bus-turnaround-ns = <0>;
 		gpmc,cycle2cycle-delay-ns = <0>;
 		gpmc,clk-activation-ns = <0>;
-		gpmc,wait-monitoring-ns = <0>;
 		gpmc,wr-data-mux-bus-ns = <0>;
 		/* MTD partition table */
 		/* All SPL-* partitions are sized to minimal length