drm/i915: Rename intel_panel_vbt_fixed_mode()

Rename intel_panel_vbt_fixed_mode() to
intel_panel_vbt_lfp_fixed_mode() to be more descriptive.
We'll have another VBT fixed mode function soon and we
don't want to confuse the two.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220323182935.4701-6-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>