dt-bindings: serial: lpuart: add imx8qxp compatible string

Add imx8qxp compatible string

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-serial@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NDong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/fsl-lpuart.txt

@@ -8,6 +8,8 @@ Required properties:
     on LS1021A SoC with 32-bit big-endian register organization
   - "fsl,imx7ulp-lpuart" for lpuart compatible with the one integrated
     on i.MX7ULP SoC with 32-bit little-endian register organization
+  - "fsl,imx8qxp-lpuart" for lpuart compatible with the one integrated
+    on i.MX8QXP SoC with 32-bit little-endian register organization
 - reg : Address and length of the register set for the device
 - interrupts : Should contain uart interrupt
 - clocks : phandle + clock specifier pairs, one for each entry in clock-names