Documentation: dt: update properties in TI GPMC NAND example

The GPMC timing properties for device-tree have been updated
by adding a "-ns" or "-ps" suffix to indicate the units of
time the property represents. Therefore, update the timing
property names for TI GPMC NAND example.
Signed-off-by: NJon Hunter <jon-hunter@ti.com>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>

Documentation/devicetree/bindings/mtd/gpmc-nand.txt

@@ -56,20 +56,20 @@ Example for an AM33xx board:
 			nand-bus-width = <16>;
 			ti,nand-ecc-opt = "bch8";
 
-			gpmc,sync-clk = <0>;
-			gpmc,cs-on = <0>;
-			gpmc,cs-rd-off = <44>;
-			gpmc,cs-wr-off = <44>;
-			gpmc,adv-on = <6>;
-			gpmc,adv-rd-off = <34>;
-			gpmc,adv-wr-off = <44>;
-			gpmc,we-off = <40>;
-			gpmc,oe-off = <54>;
-			gpmc,access = <64>;
-			gpmc,rd-cycle = <82>;
-			gpmc,wr-cycle = <82>;
-			gpmc,wr-access = <40>;
-			gpmc,wr-data-mux-bus = <0>;
+			gpmc,sync-clk-ps = <0>;
+			gpmc,cs-on-ns = <0>;
+			gpmc,cs-rd-off-ns = <44>;
+			gpmc,cs-wr-off-ns = <44>;
+			gpmc,adv-on-ns = <6>;
+			gpmc,adv-rd-off-ns = <34>;
+			gpmc,adv-wr-off-ns = <44>;
+			gpmc,we-off-ns = <40>;
+			gpmc,oe-off-ns = <54>;
+			gpmc,access-ns = <64>;
+			gpmc,rd-cycle-ns = <82>;
+			gpmc,wr-cycle-ns = <82>;
+			gpmc,wr-access-ns = <40>;
+			gpmc,wr-data-mux-bus-ns = <0>;
 
 			#address-cells = <1>;
 			#size-cells = <1>;