dt-bindings: rtc: qcom-pm8xxx: add uefi-variable offset

dt-bindings: rtc: qcom-pm8xxx: add uefi-variable offset

On many Qualcomm platforms the PMIC RTC control and time registers are
read-only so that the RTC time can not be updated. Instead an offset
needs be stored in some machine-specific non-volatile memory, which a
driver can take into account.

On platforms where the offset is stored in a Qualcomm specific UEFI
variable the variables are also accessed in a non-standard way, which
means that the OS cannot assume that the variable service is available
by the time the RTC driver probes.

Add a 'qcom,uefi-rtc-info' boolean flag to indicate that the RTC offset
is stored in a Qualcomm specific UEFI variable so that the OS can
determine whether to wait for it to become available.

The UEFI variable is

	882f8c2b-9646-435f-8de5-f208ff80c1bd-RTCInfo

and holds a 12-byte structure where the first four bytes is a GPS time
offset in little-endian byte order.

Link: https://lore.kernel.org/all/aAecIkgmTTlThKEZ@hovoldconsulting.com/
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250423075143.11157-2-johan+linaro@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>