Kinda-backport of r46415, though this patch uses the old-style calibration data loading.
Signed-off-by: Christian Beier <cb@shoutrlabs.com>

git-svn-id: svn://svn.openwrt.org/openwrt/branches/chaos_calmer@46673 3c298f89-4303-0410-b956-a3cf2f4a3e73