drm/i915/psr: Check for the specific AUX_FRAME_SYNC cap bit.

The cap check should be specifically for bit 0 instead of any bit.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Fixes: 474d1ec4a3d7 ("drm/i915/skl: Enabling PSR2 SU with frame sync")
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180223221520.18464-4-dhinakaran.pandiyan@intel.com

drivers/gpu/drm/i915/intel_psr.c

@@ -144,7 +144,7 @@ void intel_psr_init_dpcd(struct intel_dp *intel_dp)
 				      DP_SINK_DEVICE_AUX_FRAME_SYNC_CAP,
 				      &frame_sync_cap) != 1)
 			frame_sync_cap = 0;
-		dev_priv->psr.aux_frame_sync = frame_sync_cap ? true : false;
+		dev_priv->psr.aux_frame_sync = frame_sync_cap & DP_AUX_FRAME_SYNC_CAP;
 		/* PSR2 needs frame sync as well */
 		dev_priv->psr.psr2_support = dev_priv->psr.aux_frame_sync;
 		DRM_DEBUG_KMS("PSR2 %s on sink",