spi: spi-fsl-qspi: Add ls2080a compatibility string to bindings

There are 2 version of QSPI-IP, according to which controller registers sets
can be big endian or little endian.There are some other minor changes like
RX fifo depth etc.

The big endian version uses driver compatible "fsl,ls1021a-qspi" and
little endian version uses driver compatible "fsl,ls2080a-qspi"
Signed-off-by: Kuldeep Singh <kuldeep.singh@nxp.com>
Signed-off-by: Ashish Kumar <ashish.kumar@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Han Xu <han.xu@nxp.com>
Link: https://lore.kernel.org/r/1565691791-26167-1-git-send-email-Ashish.Kumar@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/spi-fsl-qspi.txt

@@ -3,9 +3,8 @@
 Required properties:
   - compatible : Should be "fsl,vf610-qspi", "fsl,imx6sx-qspi",
 		 "fsl,imx7d-qspi", "fsl,imx6ul-qspi",
-		 "fsl,ls1021a-qspi"
+		 "fsl,ls1021a-qspi", "fsl,ls2080a-qspi"
 		 or
-		 "fsl,ls2080a-qspi" followed by "fsl,ls1021a-qspi",
 		 "fsl,ls1043a-qspi" followed by "fsl,ls1021a-qspi"
   - reg : the first contains the register location and length,
           the second contains the memory mapping address and length