drm/i915/dp: Simplify computing forced DSC BPP for DP-SST

drm/i915/dp: Simplify computing forced DSC BPP for DP-SST

If dsc_compute_compressed_bpp() failed with a forced pipe BPP value
(where the forced pipe BPP value itself is valid within the min/max pipe
BPP limits), the function will also fail when called with the maximum
pipe BPP value: dsc_compute_compressed_bpp() will try all compressed
BPPs below the passed in pipe BPP value and if the function failed with
a given (low) compressed BPP value it will also fail with a compressed
BPP value higher than the one which failed already.

Based on the above remove the logic to retry computing a compressed BPP
value with the maximum pipe BPP value if computing the compressed BPP
failed already with the (lower) forced pipe BPP value.

Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20251222153547.713360-18-imre.deak@intel.com