dt-bindings: clock: imx5: fix example

Since commit:

    0e030a37

 ("can: flexcan: fix endianess detection")

the fsl,imx53-flexcan isn't compatible with the fsl,p1010-flexcan any more. As
the former accesses the IP core in Little Endian mode and the latter uses Big
Endian mode.

With the conversion of the flexcan DT bindings to yaml, the dt_binding_check
this throws the following error:

Documentation/devicetree/bindings/clock/imx5-clock.example.dt.yaml: can@53fc8000: compatible: 'oneOf' conditional failed, one must be fixed:
	['fsl,imx53-flexcan', 'fsl,p1010-flexcan'] is too long
	Additional items are not allowed ('fsl,p1010-flexcan' was unexpected)
	'fsl,imx53-flexcan' is not one of ['fsl,imx7d-flexcan', 'fsl,imx6ul-flexcan', 'fsl,imx6sx-flexcan']
	'fsl,imx53-flexcan' is not one of ['fsl,ls1028ar1-flexcan']
	'fsl,imx6q-flexcan' was expected
	'fsl,lx2160ar1-flexcan' was expected
	From schema: /builds/robherring/linux-dt-bindings/Documentation/devicetree/bindings/net/can/fsl,flexcan.yaml

The error is fixed by replacing the "fsl,p1010-flexcan" compatible
(which turned out the be incompatible) with "fsl,imx25-flexcan" in the
binding example.

Reported-by: Rob Herring <robh+dt@kernel.org>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20201111213548.1621094-1-mkl@pengutronix.de
[robh: Add "fsl,imx25-flexcan" as fallback]
Signed-off-by: Rob Herring <robh@kernel.org>