drm/i915: fix subslice mask array size

We have a subslice mask per slice, not per subslice.
MAX_SUBSLICES > MAX_SLICES, so the wrong size didn't cause any issue
apart from using extra memory.

Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181106182918.5748-1-daniele.ceraolospurio@intel.com

drivers/gpu/drm/i915/intel_device_info.h

@@ -124,7 +124,7 @@ enum intel_ppgtt {
 
 struct sseu_dev_info {
 	u8 slice_mask;
-	u8 subslice_mask[GEN_MAX_SUBSLICES];
+	u8 subslice_mask[GEN_MAX_SLICES];
 	u16 eu_total;
 	u8 eu_per_subslice;
 	u8 min_eu_in_pool;