ARM: dts: aspeed-g6: Add pinctrl settings

AST2600 supports 2 SGPIO master interfaces and 2 SGPIO slave interfaces.
Currently, only SGPIO master 1 and SGPIO slve 1 in the pinctrl dtsi.
SGPIO master 2 and slave 2 should be added in pinctrl dtsi as well.
Signed-off-by: NSteven Lee <steven_lee@aspeedtech.com>
Reviewed-by: NAndrew Jeffery <andrew@aj.id.au>
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Acked-by: NJoel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20210525055308.31069-3-steven_lee@aspeedtech.comSigned-off-by: NJoel Stanley <joel@jms.id.au>

arch/arm/boot/dts/aspeed-g6-pinctrl.dtsi

@@ -862,11 +862,21 @@
 		groups = "SGPM1";
 	};
 
+	pinctrl_sgpm2_default: sgpm2_default {
+		function = "SGPM2";
+		groups = "SGPM2";
+	};
+
 	pinctrl_sgps1_default: sgps1_default {
 		function = "SGPS1";
 		groups = "SGPS1";
 	};
 
+	pinctrl_sgps2_default: sgps2_default {
+		function = "SGPS2";
+		groups = "SGPS2";
+	};
+
 	pinctrl_sioonctrl_default: sioonctrl_default {
 		function = "SIOONCTRL";
 		groups = "SIOONCTRL";