linux-postmarketos-exynos5: upgrade to 6.1.24 (lts)

The pmaports package will follow lts releases from now on. Intermediate versions will be tagged in the gitlab.com/exynos5-mainline/linux repo.

Also enable CONFIG_LRU_GEN while we are at it (but not CONFIG_LRU_GEN_ENABLED for now).

Tested on klimtlte and odroid-xu4 by me, and on some of the other devices by @jenneron.