aries-common: updater: fix install from external sd

Don't use -f with readlink since it won't work if
the destination does not exist.

Change-Id: I1e2f16ba009108dbdc69f91202c1dd071c1361e7
aries-common: set TARGET_ARCH_LOWMEM

Change-Id: I3955d2a723d538f56426882b33121256f305b9fd