nl80211: Fix nl_mgmt handling in partial error case

nl80211: Fix nl_mgmt handling in partial error case

If Action frame registration in nl80211_mgmt_subscribe_non_ap() failed
for any frame type, the previous implementation skipped
nl80211_mgmt_handle_register_eloop() call. This is not desirable since
none of the Action frame types could be received and even worse, the
following nl80211_destroy_eloop_handle() call for nl_mgmt would likely
result in crashing the process due to the ELOOP_SOCKET_INVALID XOR
operation. This could be triggered at least in a P2P group interface
startup failure case.

Signed-hostap: Jouni Malinen <j@w1.fi>