arm64: dts: imx8mp: convert 'aips5' to 'aipstz5'

arm64: dts: imx8mp: convert 'aips5' to 'aipstz5'

Change the programming model of the "aips5" node to allow configuring
the security-related registers exposed by the AIPSTZ5 bridge. Without
this, masters such as the HIFI4 DSP will have their access to the
peripherals connected to the bridge denied after power cycling the
AUDIOMIX domain.

Co-developed-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>