P2P: Run full P2P_FIND scan after pending scan completes

P2P: Run full P2P_FIND scan after pending scan completes

If a P2P_FIND command is issued for running the initial full scan and
the attempt to start that full scan fails, the previous behavior was to
wait for the ongoing scan to complete and then continue p2p_find scan
iterations. However, this continued with the social channels scan
instead of the initial full scan. This could end up missing the full
scan completely.

Fix this by marking the full scan pending if the new scan cannot be
started immediately. Then start the initial full scan after the ongoing
scan completes before moving to social channel only scan iterations.
This applies both for the P2P_FIND_START_WITH_FULL (no specific
frequency set) and P2P_FIND_PROGRESSIVE cases since both of them start
with a single full scan round.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>