drm/i915: Drop useless HAS_PSR() check

It is safe to call intel_psr_disable() on a platform without PSR. We
don't have such a check when calling intel_psr_enable() either.

v2: Don't drop the HAS_DDI check quite yet (Rodrigo)
Reviewed-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170920151236.5864-1-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/intel_dp.c

@@ -2697,7 +2697,7 @@ static void intel_disable_dp(struct intel_encoder *encoder,
 	if (old_crtc_state->has_audio)
 		intel_audio_codec_disable(encoder);
 
-	if (HAS_PSR(dev_priv) && !HAS_DDI(dev_priv))
+	if (!HAS_DDI(dev_priv))
 		intel_psr_disable(intel_dp, old_crtc_state);
 
 	/* Make sure the panel is off before trying to change the mode. But also