drm/i915/alpm: Compute LOBF late after guardband is already determined

drm/i915/alpm: Compute LOBF late after guardband is already determined

Currently intel_alpm_lobf_compute_config() tries to account for
guardband +SCL requirements during encoder->compute_config() phase,
even before guardband is computed.
Also, LOBF depends on crtc_state->has_psr which can be modified in
encoder->compute_config_late().

Account for lobf requirements while optimizing the guardband and add
checks for final guardband in encoder->compute_config_late() phase after
the guardband and the final state of crtc_state->has_psr are already
computed.

Use crtc_state->vrr.guardband and crtc_state->set_context_latency for
the computation and add more documentation for the dependency of first
sdp position, guardband, set context latency and wake lines.

v2: Add helper to use min guardband required for lobf.
v3: Remove unrelated inadvertent changes. (Michał)
v4: Add a #FIXME note for computing wakelines based on feature. (Jouni)

Bspec:71041
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patch.msgid.link/20260204050250.762718-2-ankit.k.nautiyal@intel.com