The device has up to 5 potentially independent power supplies:
AVDD, DVDD, DVVDIO, VBAT and PVDD. The former 3 are mandatory for the
device to function. One of VBAT and PVDD should also be made available.

Regulators are enabled during probe time and will stay active except when in
suspend mode.

Futher, the chip needs to be informed about the presence of VBAT through a
bit in register 0x20a0.
Signed-off-by: Daniel Mack <daniel@zonque.org>
Link: https://lore.kernel.org/r/20220624104712.1934484-5-daniel@zonque.orgSigned-off-by: Mark Brown <broonie@kernel.org>