drm/ci: ignore Gamma test failures on Qualcomm SC7180

drm/ci: ignore Gamma test failures on Qualcomm SC7180

It seems, on SC7180 color conversion results are not included into the
CRC calculation (unlike SM8350). The fails for SC7180 already lists CTM
tests. Add gamma-related tests too.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Acked-by: Daniel Stone <daniels@collabora.com>
Patchwork: https://patchwork.freedesktop.org/patch/699820/
Link: https://lore.kernel.org/r/20260121-dpu-sc7180-ignore-gamma-v1-1-84f2cc2beeb1@oss.qualcomm.com