ARM: sun8i: A23: Add missing msgbox gate

Even though it's not mentionned in the A23 user manual, the A23 has a gate
for the AHB1 clock to the msgbox IP. Add it to the clock-indices.
Reported-by: NChen-Yu Tsai <wens@csie.org>
Reviewed-by: NChen-Yu Tsai <wens@csie.org>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/boot/dts/sun8i-a23.dtsi

@@ -62,8 +62,8 @@
 					<21>, <24>, <26>,
 					<29>, <32>, <36>,
 					<40>, <44>, <46>,
-					<52>, <54>,
-					<57>;
+					<52>, <53>,
+					<54>, <57>;
 			clock-output-names = "ahb1_mipidsi", "ahb1_dma",
 					"ahb1_mmc0", "ahb1_mmc1", "ahb1_mmc2",
 					"ahb1_nand", "ahb1_sdram",
@@ -71,8 +71,8 @@
 					"ahb1_spi1", "ahb1_otg", "ahb1_ehci",
 					"ahb1_ohci", "ahb1_ve", "ahb1_lcd",
 					"ahb1_csi", "ahb1_be",	"ahb1_fe",
-					"ahb1_gpu", "ahb1_spinlock",
-					"ahb1_drc";
+					"ahb1_gpu", "ahb1_msgbox",
+					"ahb1_spinlock", "ahb1_drc";
 		};
 
 		mbus_clk: clk@01c2015c {