mpc85xx: fix missing system import

The mac-address accessor functions were not included in the sourced
script. Fix this by importing the correct script path.

Signed-off-by: David Bauer <[email protected]>

target/linux/mpc85xx/base-files/lib/preinit/10_fix_eth_mac.sh

@@ -1,4 +1,5 @@
 . /lib/functions.sh
+. /lib/functions/system.sh
 
 preinit_set_mac_address() {
 	case $(board_name) in