wil6210: introduce separate completion for WMI

re-use of wmi_ready for both FW ready event and for wmi_call was causing
false "FW not ready" indication in case wmi_call() was invoked while reset
took place.
add wmi_call completion variable instead of re-using wmi_ready.

Change-Id: I2f896de72c2cee9e44f975b921c3ef503e5cf267
Signed-off-by: Dedy Lansky <qca_dlansky@qca.qualcomm.com>
Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Git-commit: 595026472eb74e4b57f5389af8b7c588659df243
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-testing.git


[hkadmany@codeaurora.org: trivial backport to kernel 3.10]
Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>