drm/i915/dp: Iterate DSC BPP from high to low on all platforms

Commit 1c56e9a3 ("drm/i915/dp: Get optimal link config to have best
compressed bpp") tries to find the best compressed bpp for the
link. However, it iterates from max to min bpp on display 13+, and from
min to max on other platforms. This presumably leads to minimum
compressed bpp always being chosen on display 11-12.

Iterate from high to low on all platforms to actually use the best
possible compressed bpp.

Fixes: 1c56e9a3 ("drm/i915/dp: Get optimal link config to have best compressed bpp")
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: <stable@vger.kernel.org> # v6.7+
Reviewed-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/3bba67923cbcd13a59d26ef5fa4bb042b13c8a9b.1738327620.git.jani.nikula@intel.com


(cherry picked from commit 56b0337d)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>