wil6210: support NL_60G_GEN_FW_RESET UNSPEC vendor command

Userspace can use this command to reset the FW/HW. Currently this is
supported only with WMI_ONLY FW.

The recommended way to reset the FW/HW is by interface down/up.
However there are cases where this is not allowed, specifically when
using WMI_ONLY FW. To overcome this limitation, userspace can use
NL_60G_GEN_FW_RESET instead.

Change-Id: If047beaa76bcd6c3ce567a10db919a884d5ec89d
Signed-off-by: Dedy Lansky <dlansky@codeaurora.org>