Up eth0 before trying to get URL to dot-config via DHCP (needed when switch
start without IP address)

fix missing "CONFIG_" in CONFIG_DOTCONF_SOURCE_LOCAL

run /usr/share/udhcpc/default.script when getting URL to dot-config to get
IP address to avoid another DHCP requests just to get IP.
Signed-off-by: Adam Wujek <adam.wujek@cern.ch>