drm/i915/dp: Simplify intel_dp_needs_8b10b_fec()

drm/i915/dp: Simplify intel_dp_needs_8b10b_fec()

The intel_crtc_state::fec_enable check in intel_dp_needs_8b10b_fec() is
redundant drop it: originally it ensured that the FEC enabled state for
a CRTC other than the CRTC intel_dp_needs_8b10b_fec() called for is
preserved, even if DSC is not enabled for the latter CRTC. The way FEC
gets enabled for all the CRTCs on an 8b10b MST link is changed by

commit 7c027070e98d ("drm/i915/dp_mst: Track DSC enabled status on the
MST link") and
commit 470b84af457e ("drm/i915/dp_mst: Recompute all MST link CRTCs if
DSC gets enabled on the link")

depending on intel_dsc_enabled_on_link() in intel_dp_needs_8b10b_fec()
instead of the above fec_enable check. Drop the check.

Suggested-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20251020154438.416761-1-imre.deak@intel.com