drm/msm/dpu: drop virt_formats from SSPP subblock configuration

drm/msm/dpu: drop virt_formats from SSPP subblock configuration

The virt_formats / virt_num_formats are not used by the current driver
and are not going to be used in future since formats for virtual planes
are handled in a different way, by forbidding unsupported combinations
during atomic_check. Drop those fields now.

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/621479/
Link: https://lore.kernel.org/r/20241025-dpu-virtual-wide-v6-3-0310fd519765@linaro.org