Using an arbitrary firmware command was actually very painful. One
had to change big switch() statements in cmd.c, cmdresp.c, add
structs to the big union in "struct cmd_ds_command" and add the
define for the CMD_802_11_xxx to the proper place.

With this function, this is now much easier. For now, it implements
a blocking (a.k.a. CMD_OPTION_WAITFORRSP) way where one deals directly
with command requests and response buffers. You can do everything in
one place:
Signed-off-by: Holger Schurig <hs4233@mail.mn-solutions.de>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>