drm/amdkfd: add new vega20 pci id

New vega20 id.

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

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

···
 	{ 0x66a1, &vega20_device_info },	/* Vega20 */
 	{ 0x66a2, &vega20_device_info },	/* Vega20 */
 	{ 0x66a3, &vega20_device_info },	/* Vega20 */
+	{ 0x66a4, &vega20_device_info },	/* Vega20 */
 	{ 0x66a7, &vega20_device_info },	/* Vega20 */
 	{ 0x66af, &vega20_device_info }		/* Vega20 */
 };