[40] input-mapper: Reverse sort order of display score comparator

The guess_candidates() function scores each display that an input device could be mapped to and then uses the sort_by_score() comparator to find the best option. The function expects the list to be sorted from best to worst, but the comparator currently sorts them in the opposite order. This causes the function to end up returning the worst match rather than the the best. This commit reverses the sort order of the comparator so that the best display can be returned as intended.

Closes: #1889 (closed)

(Cherry-picked from commit 64ff1f20)