dt-bindings: arm: fsl: Add msi-map device-tree binding for fsl-mc bus

dt-bindings: arm: fsl: Add msi-map device-tree binding for fsl-mc bus

The existing bindings cannot be used to specify the relationship
between fsl-mc devices and GIC ITSes.
Add a generic binding for mapping fsl-mc devices to GIC ITSes, using
msi-map property.
In addition, deprecate msi-parent property which no longer makes sense
now that we support translating the MSIs.

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Signed-off-by: Diana Craciun <diana.craciun@oss.nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Rob Herring <robh+dt@kernel.org>
Link: https://lore.kernel.org/r/20200619082013.13661-9-lorenzo.pieralisi@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>