Detect displayless ESP32-P4 boards in the board detector, Tab5X by chip revision, rename PoE-P4 display output to Display Out

[ainyan03]

Summary

Identify the ESP32-P4 boards without a built-in display in the board detector, select Tab5X by chip revision, and rename the PoE-P4 display output to Display Out.

Until now M5Unified told these boards apart by GPIO levels (G32 high: Tab5, G0 high: Unit PoE-P4, otherwise Stamp-P4), and the P4 detector list ran only when NVS held no board or a P4 display board. M5Unified will drop those checks in a follow-up PR once this is merged.

Changes

• Unit PoE-P4: confirmed by reading the IP101 Ethernet PHY ID (PHY address 1, registers 2 / 3 = 0x0243 / 0x0C54) over MDIO (MDC = G31, MDIO = G52), with both lines driven open-drain. G51 (PHY reset) is not touched. Before driving, G31 / G52 must read pulled up and G32 floating; this keeps Tab5 out, where G31 / G32 are the internal I2C bus. The result does not depend on whether the Display Out board is attached.
• Stamp-P4 / Stamp-P4X: nothing on the module can be confirmed, so it is reported only as a candidate (getBoardCandidate(); chip revision v3.0 or later: Stamp-P4X). It is never saved to NVS.
• Tab5: still confirmed by the two IO expanders. When the internal I2C bus is present and G22 (backlight enable, pulled down by a resistor) reads low, a Tab5 candidate is kept even if the expanders do not answer or the display setup fails.
• Tab5X (behavior change): selected from the chip revision (v3.0 or later), as Tab5X is Tab5 with a newer ESP32-P4. Before, Tab5X was detected as Tab5 unless a hint said otherwise, and Tab5 was saved to NVS.
• The P4 detector list now always runs and reports candidates, as on the other chips. Order: CoreP4X, Tab5, Unit PoE-P4, Stamp-P4.
• Board catalog: adds Unit PoE-P4 and Stamp-P4 / Stamp-P4X. detect_class may no longer be set on connector or button pins (external wiring or a button held at power-on changes their level); the validator rejects both. StampS3Mini's legacy_board_id is corrected to 155.
• Rename (separate commit): board_M5UnitPoEP4HDMI → board_M5UnitPoEP4DisplayOut (value 201 unchanged), M5UnitPoEP4HDMI → M5UnitPoEP4DisplayOut, M5UnitPoEP4HDMI.h → M5UnitPoEP4DisplayOut.h. The old names remain as deprecated aliases and the old header includes the new one, so existing sketches build with deprecation warnings.

Tested

• Stamp-P4 (chip v1.3), Tab5 (v1.0), Unit PoE-P4 (v1.3) with and without Display Out: detected as 150 / 22 / 148, also on the second boot with the saved hint.
• Tab5 with the display setup forced to fail: the board resolves to Tab5 through the candidate, nothing saved to NVS.
• Unit PoE-P4 + Display Out: attaches as a 1280x720 display with the new names, and with the old names (deprecation warnings only).
• Boot time with log level 3: Stamp-P4 unchanged (38 ms), Unit PoE-P4 +3 ms (40 → 43 ms) for the MDIO read.
• Builds for the versions in the upstream CI (Arduino 2.0.17 / 3.x, ESP-IDF 4.4 – 6.1). Board catalog: npm test, spec.js check.
• Not tested: CoreP4X, Tab5X, Stamp-P4X (no hardware).