drm/i915: Fix timeslots argument for DP DSC SST case

We now accept timeslots param exactly how the variable
sounds: amount of timeslots, but not ratio timeslots/64.
So for SST case(when we have all timeslots for use), it
should be 64, but not 1.
This caused some issues in the tests.

v2: Fixed comments

References: https://gitlab.freedesktop.org/drm/intel/-/issues/6860


Fixes: 52f14682 ("drm/i915: Bpp/timeslot calculation fixes for DP MST DSC")
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230109140210.25822-1-stanislav.lisovskiy@intel.com