drm/i915/lt_phy: Refactor LT PHY PLL handling to use explicit PLL state

drm/i915/lt_phy: Refactor LT PHY PLL handling to use explicit PLL state

The LT PHY implementation currently pulls PLL and port_clock
information directly from the CRTC state. This ties the PHY
programming logic too tightly to the CRTC state and makes it
harder to clearly express the PHY’s own PLL configuration.

Introduce an explicit "struct intel_lt_phy_pll_state" argument
for the PHY functions and update callers accordingly.

No functional change is intended — this is a preparatory cleanup for
to bring LT PHY PLL handling as part of PLL framework.

v2:  DP, HDMI 2.0, and HDMI FRL modes are port of the VDR configuration 0
    register. These modes are defined by bits 2:0. Decode these to
    differentiate DP and HDMI modes when programming PLL's. (Imre, Suraj)
v3: Pass port_clock as argument instead of recalculating it (Suraj)
v4: Fix checkpatch warning of line length exceeding 100 columns

BSpec: 744921
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/20260312080657.2648265-5-mika.kahola@intel.com