Remove nxp,imx-mu-rev2 compatible. This IP block is the same as the
nxp,imx-mu device, and should be handled by the same compatible
Instead, use CONFIG_HAS_MCUX to determine which HAL APIs should be used
to interact with the messaging unit IP.
Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>
