wil6210: refactor disconnect flow

Separate sending command to the fw from the event handling function to
simplify the disconnect flow and track the from_event flag correctly.

Change-Id: Iccd4277fd6acdbecbdfcf5b9150cec2976473c19
Signed-off-by: Ahmad Masri <amasri@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Git-commit: e1b43407c034650c11bc597bef319f03b8262b6c
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git


Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Lior David <liord@codeaurora.org>