Fix the bug net.dns1.pid is same as net.dns2.pid

writePidDns() does not increase the index in case first given dns
already exist in the property.

Change-Id: I1129d0042929b3ee119160e53cae0e4143c7ea88
Signed-off-by: yoonsung.nam <yoonsung.nam@samsung.com>
1 file changed