drm/i915/bxt: add revision id for A1 stepping and use it

Prefer inclusive ranges for revision checks rather than "below B0". Per
specs A2 is not used, so revid <= A1 matches revid < B0.

Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1445343722-3312-2-git-send-email-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 09bdd94..92413e5 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -6087,7 +6087,7 @@
 		break;
 	case PORT_B:
 		intel_encoder->hpd_pin = HPD_PORT_B;
-		if (IS_BROXTON(dev_priv) && (INTEL_REVID(dev) < BXT_REVID_B0))
+		if (IS_BROXTON(dev_priv) && (INTEL_REVID(dev) <= BXT_REVID_A1))
 			intel_encoder->hpd_pin = HPD_PORT_A;
 		break;
 	case PORT_C: