dt-bindings: memory: fsl: convert ifc binding to yaml schema

Convert the txt binding to yaml format and add description.  Drop the
"simple-bus" compatible string from the example and not allowed by the
binding any more.  This will help to enforce the correct probe order
between parent device and child devices, but will require the ifc driver
to probe the child devices to work properly.

Signed-off-by: Li Yang <leoyang.li@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211116211846.16335-2-leoyang.li@nxp.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>