drm/i915/skl: handle port E in cpt_digital_port_connected

SKL port E handling was added in

commit 26951caf
Author: Xiong Zhang <xiong.y.zhang@intel.com>
Date:   Mon Aug 17 15:55:50 2015 +0800

    drm/i915/skl: enable DDI-E hotplug

but the whole function was moved in a another branch in

commit b93433cc
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Thu Aug 20 10:47:36 2015 +0300

    drm/i915: move ibx_digital_port_connected to intel_dp.c

and the addition was lost at some backmerge that I was unable to
identify. Put it back in.
Tested-by: Tomi Sarvela <tomix.p.sarvela@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_dp.c

@@ -4582,6 +4582,9 @@ static bool cpt_digital_port_connected(struct drm_i915_private *dev_priv,
 	case PORT_D:
 		bit = SDE_PORTD_HOTPLUG_CPT;
 		break;
+	case PORT_E:
+		bit = SDE_PORTE_HOTPLUG_SPT;
+		break;
 	default:
 		MISSING_CASE(port->port);
 		return false;