drm/i915: Drop the pointless linetime==0 check

0*whatever==0 so this check is pointless. Remove it.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181221171436.8218-9-ville.syrjala@linux.intel.comReviewed-by: NMatt Roper <matthew.d.roper@intel.com>

drivers/gpu/drm/i915/intel_pm.c

@@ -4824,10 +4824,6 @@ skl_compute_linetime_wm(const struct intel_crtc_state *cstate)
 	u32 linetime_wm;
 
 	linetime_us = intel_get_linetime_us(cstate);
-
-	if (is_fixed16_zero(linetime_us))
-		return 0;
-
 	linetime_wm = fixed16_to_u32_round_up(mul_u32_fixed16(8, linetime_us));
 
 	/* Display WA #1135: bxt:ALL GLK:ALL */