dt-bindings: bus: Add Freescale i.MX8qxp pixel link MSI bus binding

dt-bindings: bus: Add Freescale i.MX8qxp pixel link MSI bus binding

Freescale i.MX8qxp pixel link MSI bus is a simple memory-mapped bus.
It is used to access peripherals in i.MX8qm/qxp imaging, LVDS, MIPI
DSI and HDMI TX subsystems, like I2C controller, PWM controller,
MIPI DSI controller and Control and Status Registers (CSR) module.

Reference simple-pm-bus bindings and add Freescale i.MX8qxp pixel
link MSI bus specific bindings.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Liu Ying <victor.liu@nxp.com>
Link: https://lore.kernel.org/r/20221017074039.4181843-3-victor.liu@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>