drm/amdgpu: add bad gpu tag definition

This tag will be hired for bad gpu detection in eeprom's access.
Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ras_eeprom.c

@@ -46,6 +46,9 @@
 #define EEPROM_TABLE_HDR_VAL 0x414d4452
 #define EEPROM_TABLE_VER 0x00010000
 
+/* Bad GPU tag ‘BADG’ */
+#define EEPROM_TABLE_HDR_BAD 0x42414447
+
 /* Assume 2 Mbit size */
 #define EEPROM_SIZE_BYTES 256000
 #define EEPROM_PAGE__SIZE_BYTES 256