P2P: Remove pending p2p-listen radio work on stopping listen

P2P: Remove pending p2p-listen radio work on stopping listen

Some kind of race condition seemed to be hit at least in test sequence
"p2p_ext_vendor_elem_invitation pasn_comeback_after_0_sae" where the P2P
invitation response could have been received just after having scheduled
a new p2p-listen radio work, but before that work had been started. In
the case of accepted invitation, this could result in unnecessary extra
delay when that p2p-listen work ended up getting started at the exact
time that the local device was starting GO.

Avoid this race condition by removing the pending p2p-listen radio work
when P2P listen is stopped.

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