drm/xe/kunit: Test WAs for BMG

Add one variant for BMG to make sure the workarounds do not conflict.
This matches the machine with BMG in CI:

BATTLEMAGE e20b:0000 dgfx:1
gfx:Xe2_LPG / Xe2_HPG (20.01)
media:Xe2_LPM / Xe2_HPM (13.01)
display:yes dma_m_s:46 tc:1 gscfi:0 cscfi:1
Stepping = (G:A0, M:A1, D:**, B:**)

Reviewed-by: Gustavo Sousa <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Lucas De Marchi <[e-mail]>

drivers/gpu/drm/xe/tests/xe_wa_test.c

···
 	GMDID_CASE(METEORLAKE, 1274, A0, 1300, A0),
 	GMDID_CASE(LUNARLAKE, 2004, A0, 2000, A0),
 	GMDID_CASE(LUNARLAKE, 2004, B0, 2000, A0),
+	GMDID_CASE(BATTLEMAGE, 2001, A0, 1301, A1),
 };
 
 static void platform_desc(const struct platform_test_case *t, char *desc)