net: app: Fix issue while configuring local context

When IPv6 and IPv4 both are enabled and net_app acting as a client,
configuring local context has one glitch.

After selection of IPv6 context as a default context  function
should return immediately, otherwise it continue to select IPv4
context as default context.

Signed-off-by: Ravi kumar Veeramally <ravikumar.veeramally@linux.intel.com>