linux-gbmc: 5.15: Add TPS53679 linear mode, TPS53685, and TPS53686

Split TPS53679 enhancements into two patches:
1. Dynamic linear mode detection in tps53679_identify_mode() based on
   VOUT_MODE register (PB_VOUT_MODE_LINEAR).
2. Global support for TPS53685 and TPS53686 controllers:
   - Enable PMBUS_HAVE_TEMP2 (temp3) on page 0 for controller die temperature.
   - Enable dual-page VIN/IIN/PIN/STATUS_INPUT telemetry on page 1.
   - Add chip ID and device tree compatible entries for TPS53685 and TPS53686.

Google-Bug-Id: 467801199
Signed-off-by: William A. Kennington III <wak@google.com>
Tested: Built image and verified TPS53686 telemetry live on hardware.
Change-Id: Ia89544b7330efeb5a84eba66603fba6dc6f5b64f