Add a driver for the FP9931/JD9930 regulator which provides the
comparatively high voltages needed for electronic paper displays.

Datasheet for the FP9931 is at
https://www.fitipower.com/dl/file/flXa6hIchVeu0W3K

Although it is in English, it seems to be only downloadable
from the Chinese part of that website. 
For the JD9930 there can be a datasheet found at
https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/196/JD9930_2D00_0.7_2D00_JUN_2D00_2019.pdf

To simplify things, include the hwmon part directly which is only
one register read and there are not other functions besides
regulators in this chip.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
---
Andreas Kemnade (3):
      dt-bindings: vendor-prefixes: Add Fitipower
      dt-bindings: regulator: Add Fitipower FP9931/JD9930
      regulator: Add FP9931/JD9930 driver

 .../devicetree/bindings/regulator/fiti,fp9931.yaml | 133 +++++
 .../devicetree/bindings/vendor-prefixes.yaml       |   2 +
 drivers/regulator/Kconfig                          |  10 +
 drivers/regulator/Makefile                         |   1 +
 drivers/regulator/fp9931.c                         | 567 +++++++++++++++++++++
 5 files changed, 713 insertions(+)
---
base-commit: dcb6fa37fd7bc9c3d2b066329b0d27dedf8becaa
change-id: 20251107-fp9931-submit-0ac249b5d6b0

Best regards,
--  
Andreas Kemnade <andreas@kemnade.info>