gw6c: fixed sed separator

On my ramips RT5350 HAME-MPR1 target, my build directory is:
"build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2", thus the problem.

Signed-off-by: Michel Stempin <michel.stempin@wanadoo.fr>


git-svn-id: svn://svn.openwrt.org/openwrt/packages@39657 3c298f89-4303-0410-b956-a3cf2f4a3e73