P2P: Make the default p2p_find delay value configurable

P2P: Make the default p2p_find delay value configurable

This makes the p2p_find default delay value configurable as
p2p_search_delay parameter through the configuration file (and through
control interface "SET p2p_search_delay <value>" on the P2P management
interface.

This parameter controls the number milliseconds of extra delay that is
added between search iterations when there is a concurrent operation in
progress. This can be used, e.g., p2p_search_delay=100 to make p2p_find
friendlier to concurrent operations by avoiding it from taking 100% of
the radio resources. The default value is the previous default, i.e.,
500 ms. Smaller values can be used to find peers more quickly at the
cost of larger effect to concurrent operations while a larger value
leaves more time for the concurrent operations at the cost of making
device discovery take longer time.

The optional p2p_find delay argument can still be used to override the
search delay for each search operation.

Since the P2P_CONCURRENT_SEARCH_DELAY macro is not used anymore, the
driver specific build parameter for bcmdhd from Android.mk is also
removed. Similar configuration can now be achieved with
p2p_search_delay=0 in the p2p0 interface configuration file.

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