drm/i915: Drop redundant !modeset check

Since commit 7de5b6b5 ("drm/i915: Don't flag both full
modeset and fastset at the same time")
intel_crtc_needs_fastset() and intel_crtc_needs_modeset() have
been mutually exclusive. Drop the redundant check.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230907122541.32261-2-ville.syrjala@linux.intel.comReviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

drivers/gpu/drm/i915/display/intel_display.c

@@ -6831,7 +6831,7 @@ static void intel_update_crtc(struct intel_atomic_state *state,
 	 * valid pipe configuration from the BIOS we need to take care
 	 * of enabling them on the CRTC's first fastset.
 	 */
-	if (intel_crtc_needs_fastset(new_crtc_state) && !modeset &&
+	if (intel_crtc_needs_fastset(new_crtc_state) &&
 	    old_crtc_state->inherited)
 		intel_crtc_arm_fifo_underrun(crtc, new_crtc_state);
 }