drm/xe/kunit: Test WAs for BMG

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 <gustavo.sousa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240727015907.899192-2-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>