arm64: dts: allwinner: pinephone: Add mount matrix to accelerometer

The way InvenSense MPU-6050 accelerometer is mounted on the user-facing side
of the Pine64 PinePhone mainboard, which makes it rotated 90 degrees counter-
clockwise, [1] requires the accelerometer's x- and y-axis to be swapped, and
the direction of the accelerometer's y-axis to be inverted.

Rectify this by adding a mount-matrix to the accelerometer definition in the
Pine64 PinePhone dtsi file.

[1] https://files.pine64.org/doc/PinePhone/PinePhone%20mainboard%20bottom%20placement%20v1.1%2020191031.pdf

Fixes: 91f480d40942 ("arm64: dts: allwinner: Add initial support for Pine64 PinePhone")
Cc: [e-mail]
Suggested-by: Ondrej Jirman <[e-mail]>
Suggested-by: Andrey Skvortsov <[e-mail]>
Signed-off-by: Dragan Simic <[e-mail]>
Reviewed-by: Andrey Skvortsov <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
[[e-mail]: Replaced Helped-by with Suggested-by]
Signed-off-by: Chen-Yu Tsai <[e-mail]>

arch/arm64/boot/dts/allwinner/sun50i-a64-pinephone.dtsi

···
 		interrupts = <7 5 IRQ_TYPE_EDGE_RISING>; /* PH5 */
 		vdd-supply = <&reg_dldo1>;
 		vddio-supply = <&reg_dldo1>;
+		mount-matrix = "0", "1", "0",
+			       "-1", "0", "0",
+			       "0", "0", "1";
 	};
 };