Replace the hard stub in display.rs::read_edid_block() with a real
GMBUS I2C EDID read. Fixes the #1 plan gap identified in the
code quality audit.
- display.rs: add gmbus: Option<GmbusController> to IntelDisplay
struct and new() constructor. read_edid_block() now calls
gmbus.read_edid() via GymbusPort::from_connector_index().
Falls back to DriverError if no GMBUS controller available.
- mod.rs: pass gmbus controller (cloned) to IntelDisplay::new()
This completes the EDID path for Gen9 platforms (Gen8-9 have
GMBUS, Xe2 uses DP AUX). The synthetic 1080p fallback remains
as the final safety net.
vasilito
0dee6ec9da