arm64: dts: marvell: armada-37xx: add device node for UART clock and use it

Define DT node for UART clock "marvell,armada-3700-uart-clock" and use
this UART clock as a base clock for all UART devices.
Reviewed-by: NMarek Behún <kabel@kernel.org>
Acked-by: NGregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: NPali Rohár <pali@kernel.org>
Signed-off-by: NMarek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/20220219152818.4319-7-kabel@kernel.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm64/boot/dts/marvell/armada-37xx.dtsi

@@ -132,10 +132,20 @@
 				reg = <0x11500 0x40>;
 			};
 
+			uartclk: clock-controller@12010 {
+				compatible = "marvell,armada-3700-uart-clock";
+				reg = <0x12010 0x4>, <0x12210 0x4>;
+				clocks = <&tbg 0>, <&tbg 1>, <&tbg 2>,
+					 <&tbg 3>, <&xtalclk>;
+				clock-names = "TBG-A-P", "TBG-B-P", "TBG-A-S",
+					      "TBG-B-S", "xtal";
+				#clock-cells = <1>;
+			};
+
 			uart0: serial@12000 {
 				compatible = "marvell,armada-3700-uart";
 				reg = <0x12000 0x18>;
-				clocks = <&xtalclk>;
+				clocks = <&uartclk 0>;
 				interrupts =
 				<GIC_SPI 11 IRQ_TYPE_LEVEL_HIGH>,
 				<GIC_SPI 12 IRQ_TYPE_LEVEL_HIGH>,
@@ -147,7 +157,7 @@
 			uart1: serial@12200 {
 				compatible = "marvell,armada-3700-uart-ext";
 				reg = <0x12200 0x30>;
-				clocks = <&xtalclk>;
+				clocks = <&uartclk 1>;
 				interrupts =
 				<GIC_SPI 30 IRQ_TYPE_EDGE_RISING>,
 				<GIC_SPI 31 IRQ_TYPE_EDGE_RISING>;