[PATCH] regulator: qcom-rpmh: Add support for regulator-off-on-delay-us

[Saikiran <bjsaikiran@gmail.com>]

This patch adds support for the generic `regulator-off-on-delay-us` property
to the Qualcomm RPMh regulator driver.

The core regulator framework supports enforcing a physical off-time via
standard properties, but the `qcom-rpmh-regulator` driver currently ignores
them. This prevents boards with slow-discharging rails from enforcing safe
power-cycling constraints.

Motivation / Test Result:
On the Lenovo Yoga Slim 7x (Snapdragon X Elite), the camera regulators
rely on passive discharge and require a significant off-time to drop below
brownout thresholds.

I have tested this patch on the Yoga Slim 7x. When the delay property is
present in the device tree, the regulator core correctly blocks re-enable
calls until the delay passes. This successfully fixes the camera brownout
issues and allows reliable sensor initialization during rapid power cycling.

I am submitting this driver support first to ensure the mechanism is available.
Once the consumer nodes (camera) for this board are upstream, we will apply
the specific delay values in the DTS.

Saikiran (1):
  regulator: qcom-rpmh: Add support for regulator-off-on-delay-us