Tweak the lua regex string for process list, so that processes
with extremely large memory sizes (over 100 MB) are matched.
For those large processes busybox top shows a MB value like '234m'
instead of a normal kB value like 234000.
Fixes#4425
Reference to https://github.com/openwrt/luci/issues/4425#issuecomment-694073479
Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>