drm/i915/glk: Remove the alpha_support flag

Geminilake is now included in CI, making it part of the pre-merge
criteria. The support should be in good enough shape, so let's remove
the alpha_support flag.
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170608114800.17201-1-ander.conselvan.de.oliveira@intel.com

drivers/gpu/drm/i915/i915_pci.c

@@ -400,7 +400,6 @@ static const struct intel_device_info intel_broxton_info = {
 static const struct intel_device_info intel_geminilake_info = {
 	GEN9_LP_FEATURES,
 	.platform = INTEL_GEMINILAKE,
-	.is_alpha_support = 1,
 	.ddb_size = 1024,
 	.color = { .degamma_lut_size = 0, .gamma_lut_size = 1024 }
 };