ARM: dts: imx6: set ahb-burst-config as 0 for USB

After setting ahb burst configuration as 0, we can increase tx/rx
burst size, it will improve the USB performance

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6ul.dtsi

@@ -548,6 +548,7 @@
 				fsl,usbphy = <&usbphy1>;
 				fsl,usbmisc = <&usbmisc 0>;
 				fsl,anatop = <&anatop>;
+				ahb-burst-config = <0x0>;
 				status = "disabled";
 			};
 
@@ -558,6 +559,7 @@
 				clocks = <&clks IMX6UL_CLK_USBOH3>;
 				fsl,usbphy = <&usbphy2>;
 				fsl,usbmisc = <&usbmisc 1>;
+				ahb-burst-config = <0x0>;
 				status = "disabled";
 			};