arm64: zynqmp: Set qspi tx-buswidth to 4

In all the ZynqMP boards dts files tx-buswidth is by default set to 1. Due
to this the framework only issues 1-1-1 write commands to the GQSPI driver.
But the GQSPI controller is capable of handling 1-4-4 write commands, so
updated the tx-buswidth to 4 in ZynqMP boards dts files. This would enable
the spi-nor framework to issue 1-4-4 write commands instead of 1-1-1. This
will increase the tx data transfer rate, as now the tx data will be
transferred on four lines instead on single line.

Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@xilinx.com>
Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/ad61199f55e5e00f29de6206d9d1872a52a7657e.1652193179.git.michal.simek@amd.com
diff --git a/arch/arm/dts/zynqmp-sm-k26-revA.dts b/arch/arm/dts/zynqmp-sm-k26-revA.dts
index 14ab316..e904cd8 100644
--- a/arch/arm/dts/zynqmp-sm-k26-revA.dts
+++ b/arch/arm/dts/zynqmp-sm-k26-revA.dts
@@ -117,7 +117,7 @@
 		#address-cells = <1>;
 		#size-cells = <1>;
 		reg = <0>;
-		spi-tx-bus-width = <1>;
+		spi-tx-bus-width = <4>;
 		spi-rx-bus-width = <4>;
 		spi-max-frequency = <40000000>; /* 40MHz */
 		partition@0 {