ARM: dts: pxa*: Make the serial ports compatible with xscale-uart

Some drivers that claim to support mrvl,mmp-uart default to a reg-shift
of two, some don't. Be explicit to be on a safe side.

With that in place, a XScale serial port driver is perfectly capable of
supporting the MMP serial port. Add a compatible string.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200320174107.29406-4-lkundrak@v3.skSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm/boot/dts/pxa168.dtsi

@@ -56,8 +56,9 @@ timer0: timer@d4014000 {
 			};
 
 			uart1: serial@d4017000 {
-				compatible = "mrvl,mmp-uart";
+				compatible = "mrvl,mmp-uart", "intel,xscale-uart";
 				reg = <0xd4017000 0x1000>;
+				reg-shift = <2>;
 				interrupts = <27>;
 				clocks = <&soc_clocks PXA168_CLK_UART0>;
 				resets = <&soc_clocks PXA168_CLK_UART0>;
@@ -65,8 +66,9 @@ uart1: serial@d4017000 {
 			};
 
 			uart2: serial@d4018000 {
-				compatible = "mrvl,mmp-uart";
+				compatible = "mrvl,mmp-uart", "intel,xscale-uart";
 				reg = <0xd4018000 0x1000>;
+				reg-shift = <2>;
 				interrupts = <28>;
 				clocks = <&soc_clocks PXA168_CLK_UART1>;
 				resets = <&soc_clocks PXA168_CLK_UART1>;
@@ -74,8 +76,9 @@ uart2: serial@d4018000 {
 			};
 
 			uart3: serial@d4026000 {
-				compatible = "mrvl,mmp-uart";
+				compatible = "mrvl,mmp-uart", "intel,xscale-uart";
 				reg = <0xd4026000 0x1000>;
+				reg-shift = <2>;
 				interrupts = <29>;
 				clocks = <&soc_clocks PXA168_CLK_UART2>;
 				resets = <&soc_clocks PXA168_CLK_UART2>;

arch/arm/boot/dts/pxa910.dtsi

@@ -68,8 +68,9 @@ timer1: timer@d4016000 {
 			};
 
 			uart1: serial@d4017000 {
-				compatible = "mrvl,mmp-uart";
+				compatible = "mrvl,mmp-uart", "intel,xscale-uart";
 				reg = <0xd4017000 0x1000>;
+				reg-shift = <2>;
 				interrupts = <27>;
 				clocks = <&soc_clocks PXA910_CLK_UART0>;
 				resets = <&soc_clocks PXA910_CLK_UART0>;
@@ -77,8 +78,9 @@ uart1: serial@d4017000 {
 			};
 
 			uart2: serial@d4018000 {
-				compatible = "mrvl,mmp-uart";
+				compatible = "mrvl,mmp-uart", "intel,xscale-uart";
 				reg = <0xd4018000 0x1000>;
+				reg-shift = <2>;
 				interrupts = <28>;
 				clocks = <&soc_clocks PXA910_CLK_UART1>;
 				resets = <&soc_clocks PXA910_CLK_UART1>;
@@ -86,8 +88,9 @@ uart2: serial@d4018000 {
 			};
 
 			uart3: serial@d4036000 {
-				compatible = "mrvl,mmp-uart";
+				compatible = "mrvl,mmp-uart", "intel,xscale-uart";
 				reg = <0xd4036000 0x1000>;
+				reg-shift = <2>;
 				interrupts = <59>;
 				clocks = <&soc_clocks PXA910_CLK_UART2>;
 				resets = <&soc_clocks PXA910_CLK_UART2>;