[][Cheetah][modify min_free_kbytes to more suitable for projects with less memory]

[Description]
Change min_free_kbytes to more suitable for Cheetah
1. 256M: change to 4MiB
2. 128M: change to 2MiB

[Release-log]

Change-Id: I1b71a81c1ef16078e4cf1e9f0f353d67adf10161
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5633593
1 file changed