SCMIv2.0 adds a new Reset Management Protocol to manage various reset
states a given device or domain can enter. Device(s) that can be
collectively reset through a common reset signal constitute a reset
domain for the firmware.

A reset domain can be reset autonomously or explicitly through assertion
and de-assertion of the signal. When autonomous reset is chosen, the
firmware is responsible for taking the necessary steps to reset the
domain and to subsequently bring it out of reset. When explicit reset is
chosen, the caller has to specifically assert and then de-assert the
reset signal by issuing two separate RESET commands.

Add the basic SCMI reset infrastructure that can be used by Linux
reset controller driver.
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>