drm/i915/dp: Drop compute_pipe_bpp parameter from intel_dp_dsc_compute_config()

The parameter is basically just a proxy for whether the function is
being called for DP SST or DP MST. We can figure this out from crtc
state.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/82a4b84711b1416bb3382f5d8383fe65ab88159a.1738327620.git.jani.nikula@intel.com