staging/wilc1000: pass struct wilc to most linux_wlan.c functions

We want to get rid of all global variables in this driver, and
instead pass device structures from one function to another.
This changes the linux_wlan.c and wilc_wlan.c to do this
for the most part. There are a few exceptions where these
functions are themselves called from another part of the driver
that does not have an instance pointer at hand. Changing those
would be a follow-up step.

There are a few other globals that will have to get moved
into struct wilc at a later point.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>