wil6210: Initialize reply struct of the WMI commands

WMI command reply saved in uninitialized struct.
In order to avoid accessing unset values from FW initialize
the reply struct.

Change-Id: I4c5b22da327cc7a8c1f64c940247acef518e2ebd
Signed-off-by: Alexei Avshalom Lazar <ailizaro@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Git-commit: 807b086053df9bdbc9bf732130e9acda1c161aa5
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git
[merez@codeaurora.org: trivial conflict fixes]