[v2] Add support for hwrng on PolarFire SoC

[conor.dooley at microchip.com]

From: Conor Dooley <conor.dooley at microchip.com>

As it says on the tin, add support for the hardware rng on PolarFire
SoC, which is accessed via the system controller.
I dropped the maintainers entry change that v1 had, I will send a
single update via RISCV to avoid any conflicts.

On v1 I replied saying there was a refcount issue, but that's not
actually the case, so no changes required there.

Thanks,
Conor

Changes since v1:
- Rebased on v5.18-rc1
- Dropped the MAINTAINERS change
- Added quality estimation

Conor Dooley (1):
  hwrng: mpfs - add polarfire soc hwrng support

 drivers/char/hw_random/Kconfig    |  13 ++++
 drivers/char/hw_random/Makefile   |   1 +
 drivers/char/hw_random/mpfs-rng.c | 104 ++++++++++++++++++++++++++++++
 3 files changed, 118 insertions(+)
 create mode 100644 drivers/char/hw_random/mpfs-rng.c

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2.35.1