ARM: dts: omap3-n900: correct the accelerometer orientation

Negate the values reported for the accelerometer z-axis in order to
match Documentation/devicetree/bindings/iio/mount-matrix.txt.

Fixes: 14a213dcb0 ("ARM: dts: n900: use iio driver for accelerometer")

Signed-off-by: Sicelo A. Mhlongo <absicsz@gmail.com>
Reviewed-By: Andreas Kemnade <andreas@kemnade.info>
Link: https://lore.kernel.org/r/20240722113137.3240847-1-absicsz@gmail.com
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

arch/arm/boot/dts/ti/omap/omap3-n900.dts

@@ -781,7 +781,7 @@
 
 		mount-matrix =	 "-1",  "0",  "0",
 				  "0",  "1",  "0",
-				  "0",  "0",  "1";
+				  "0",  "0",  "-1";
 	};
 
 	cam1: camera@3e {