drm/tests: Split drm_test_dp_mst_calc_pbn_mode into parameterized tests

The drm_test_dp_mst_calc_pbn_mode is based on a loop that executes tests
for a couple of test cases. This could be better represented by
parameterized tests, provided by KUnit.

So, convert the drm_test_dp_mst_calc_pbn_mode into parameterized tests.

Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20221001223422.857505-1-mcanal@igalia.com