target: globally remove ARCH_PACKAGES overrides

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

adm5120: enable low_mem

Most devices have only 16 MiB of RAM, this will allow them to boot
without OOM.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44587 3c298f89-4303-0410-b956-a3cf2f4a3e73

adm5120: create a new subtarget for the RB1xx devices

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@31513 3c298f89-4303-0410-b956-a3cf2f4a3e73