dt-bindings: cadence-quadspi: Add new compatible for AM654 SoC

AM654 SoC has Cadence Octal SPI controller, which is similar to Cadence
QSPI controller but supports Octal IO(x8 data lines) and Double Data
Rate(DDR) mode. Add new compatible to support OSPI controller on TI's
AM654 SoCs.
Signed-off-by: Vignesh R <vigneshr@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>

Documentation/devicetree/bindings/mtd/cadence-quadspi.txt

@@ -4,6 +4,7 @@ Required properties:
 - compatible : should be one of the following:
 	Generic default - "cdns,qspi-nor".
 	For TI 66AK2G SoC - "ti,k2g-qspi", "cdns,qspi-nor".
+	For TI AM654 SoC  - "ti,am654-ospi", "cdns,qspi-nor".
 - reg : Contains two entries, each of which is a tuple consisting of a
 	physical address and length. The first entry is the address and
 	length of the controller register set. The second entry is the