drm/i915: Fixes to support DP Compliance EDID tests

This patch addresses a few issues from the original patch for
DP Compliance EDID test support submitted by
Todd Previte<todd.previte@gmail.com>

Video Mode requested in the EDID test handler for the EDID Read
test (CTS 4.2.2.3) should be set to PREFERRED as per the CTS spec.

v2:
* Added read debugfs data from test_data.edid if its EDID test (Jani NIkula)
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1484968170-12467-3-git-send-email-manasi.d.navare@intel.com
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 6d99146..726256f 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3775,7 +3775,10 @@ static int i915_displayport_test_data_show(struct seq_file *m, void *data)
 		if (connector->status == connector_status_connected &&
 		    connector->encoder != NULL) {
 			intel_dp = enc_to_intel_dp(connector->encoder);
-			seq_printf(m, "%lx", intel_dp->compliance.test_data.edid);
+			if (intel_dp->compliance.test_type ==
+			    DP_TEST_LINK_EDID_READ)
+				seq_printf(m, "%lx",
+					   intel_dp->compliance.test_data.edid);
 		} else
 			seq_puts(m, "0");
 	}