remoteproc: renesas: Add Renesas R-Car Gen5 remote processor driver

remoteproc: renesas: Add Renesas R-Car Gen5 remote processor driver

Add R-Car Gen5 RSIP controller remoteproc driver capable of starting
the SCP, Cortex-R52 and Cortex-A720 cores in Renesas R-Car R8A78000
X5H SoC. The SCP core is started by releasing the core from reset,
the Cortex-R52 and Cortex-A720 are started using the SCP SCMI call.
The entry point for SCP core is fixed to its STCM, entry points for
Cortex-R52 and Cortex-A720 are set during rproc load.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>