arm64: dts: salvator-x: Add missing index to PWM pinctrl subnode name

R-Car Gen3 SoCs contain multiple PWM modules.  Hence to avoid conflicts,
pinctrl subnodes for PWM should include indices referring to their
instances.

Fixes: b33be336 ("arm64: dts: salvator-x: Add panel backlight support")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/salvator-x.dtsi

@@ -417,7 +417,7 @@ i2c2_pins: i2c2 {
 		function = "i2c2";
 	};
 
-	pwm1_pins: pwm {
+	pwm1_pins: pwm1 {
 		groups = "pwm1_a";
 		function = "pwm1";
 	};