drm/amdkfd: Reconcile the definition and use of oem_id in struct kfd_topology_device

Currently oem_id is defined as uint8_t[6] and casted to uint64_t*
in some use case. This would lead code scanner to complain about
access beyond. Re-define it in union to enforce 8-byte size and
alignment to avoid potential issue.

Signed-off-by: Michael Chen <[e-mail]>
Reviewed-by: Felix Kuehling <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdkfd/kfd_crat.h

···
 #define CRAT_OEMTABLEID_LENGTH	8
 #define CRAT_RESERVED_LENGTH	6
 
-#define CRAT_OEMID_64BIT_MASK ((1ULL << (CRAT_OEMID_LENGTH * 8)) - 1)
-
 /* Compute Unit flags */
 #define COMPUTE_UNIT_CPU	(1 << 0)  /* Create Virtual CRAT for CPU */
 #define COMPUTE_UNIT_GPU	(1 << 1)  /* Create Virtual CRAT for GPU */

drivers/gpu/drm/amd/amdkfd/kfd_topology.c

···
 	dev = list_last_entry(&topology_device_list,
 			struct kfd_topology_device, list);
 	if (dev) {
-		sys_props.platform_id =
-			(*((uint64_t *)dev->oem_id)) & CRAT_OEMID_64BIT_MASK;
+		sys_props.platform_id = dev->oem_id64;
 		sys_props.platform_oem = *((uint64_t *)dev->oem_table_id);
 		sys_props.platform_rev = dev->oem_revision;
 	}

drivers/gpu/drm/amd/amdkfd/kfd_topology.h

···
 	struct attribute		attr_gpuid;
 	struct attribute		attr_name;
 	struct attribute		attr_props;
-	uint8_t				oem_id[CRAT_OEMID_LENGTH];
+	union {
+		uint8_t				oem_id[CRAT_OEMID_LENGTH];
+		uint64_t			oem_id64;
+	};
 	uint8_t				oem_table_id[CRAT_OEMTABLEID_LENGTH];
 	uint32_t			oem_revision;
 };