drm/i915: Fix uninitialized mask in intel_device_info_subplatform_init

Mask need to be initialized to zero since device id checks may not match.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 805446c8 ("drm/i915: Introduce concept of a sub-platform")
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Jose Souza <jose.souza@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190403064407.25646-1-tvrtko.ursulin@linux.intel.com

drivers/gpu/drm/i915/intel_device_info.c

@@ -778,7 +778,7 @@ void intel_device_info_subplatform_init(struct drm_i915_private *i915)
 	const unsigned int pi = __platform_mask_index(rinfo, info->platform);
 	const unsigned int pb = __platform_mask_bit(rinfo, info->platform);
 	u16 devid = INTEL_DEVID(i915);
-	u32 mask;
+	u32 mask = 0;
 
 	/* Make sure IS_<platform> checks are working. */
 	RUNTIME_INFO(i915)->platform_mask[pi] = BIT(pb);