staging: wfx: do not wait for a dtim before associate

The only reason we ask to mac80211 to wait for a dtim before to
associate is to get an accurate DTIM value. However, we can temporary
set the dtim period to 1. Then we can waiting for
BSS_CHANGED_BEACON_INFO for the real value. Thus, the association
process is faster.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200415161147.69738-7-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>