base-files: flush kernel memory cache during sysupgrade

[Hannu Nyman]

Stijn Segers kirjoitti 13.1.2021 klo 0.48:
> Have tested this on a few low-RAM devices, among which a TL-WR841N v7 (32 
> MiB) and a WNDR3700 v2 (64 MiB).
>
> No idea if this is still necessary/wanted but would be nice to see this end 
> up in master (and trickle down to 21.xx :-D ).
>
> Tested-by: Stijn Segers <foss at volatilesystems.org>

Hi Stijn,

this has been merged already in December as commit 3d12b4798:

https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=3d12b47985fc1983849925d2dc23430f55210c80