drm/i915/psr: Add helper to get min psr guardband

drm/i915/psr: Add helper to get min psr guardband

Introduce a helper to compute the max link wake latency when using
Auxless/Aux wake mechanism for PSR/Panel Replay/LOBF features.

This will be used to compute the minimum guardband so that the link wake
latencies are accounted and these features work smoothly for higher
refresh rate panels.

v2:
- Account for flag `req_psr2_sdp_prior_scanline` and scl lines while
  computing min guardband. (Jouni)
- Use wake lines only for eDP with panel_replay and sel_update flags
  set. (Jouni)

Bspec: 70151, 71477
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://lore.kernel.org/r/20251017123504.2247954-2-ankit.k.nautiyal@intel.com