P2P: Fix segfault when PBC overlap is detected

If a separate P2P group interface is used, PBC overlap during group
formation causes the group interface to be removed, which ends up with
the interface context becoming invalid. Fix this by scheduling a timeout
to process the PBC overlap and interface removal instead of removing the
interface directly before the connection operation has returned.

Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Git-commit: ace0fbdb69b492a3aa6f24d07f0d6d4dffc4b7dc
Git-repo : git://w1.fi/srv/git/hostap.git
Change-Id: Iee452eb1ea731c7e216e0ec25a7c7235756589ac
CRs-fixed: 670339