dt-bindings: firmware: Add i.MX95 SCMI Extension protocol

Add i.MX SCMI Extension protocols bindings for:
- Battery Backed Module(BBM) Protocol
  This contains persistent storage (GPR), an RTC, and the ON/OFF button.
  The protocol can also provide access to similar functions implemented via
  external board components.
- MISC Protocol.
  This includes controls that are misc settings/actions that must be
  exposed from the SM to agents. They are device specific and are usually
  define to access bit fields in various mix block control modules,
  IOMUX_GPR, and other GPR/CSR owned by the SM.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Message-Id: <20240823-imx95-bbm-misc-v2-v8-1-e600ed9e9271@nxp.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>