drm/i915/bios: assume eDP is present on port A when there is no VBT

We rely on VBT DDI port info for eDP detection on GEN9 platforms and
above. This breaks GEN9 platforms which don't have VBT because port A
eDP now defaults to false. Fix this by defaulting to true when VBT is
missing.

Fixes: a98d9c1d ("drm/i915/ddi: Rely on VBT DDI port info for eDP detection")
Signed-off-by: NThomas Preston <thomas.preston@codethink.co.uk>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190306200618.17405-1-thomas.preston@codethink.co.uk
(cherry picked from commit 2131bc0c)
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/intel_bios.c

@@ -1673,6 +1673,7 @@ init_vbt_missing_defaults(struct drm_i915_private *dev_priv)
 		info->supports_dvi = (port != PORT_A && port != PORT_E);
 		info->supports_hdmi = info->supports_dvi;
 		info->supports_dp = (port != PORT_E);
+		info->supports_edp = (port == PORT_A);
 	}
 }