staging: wilc1000: move all of wilc_wlan_dev_t to struct wilc

linux_wlan.c and wilc_wlan.c was separated into two part at the beginning
to support various platforms. They are in charge of send/receive control and
packet data, so they will be merged into one file wlan.c later.
First of all, wilc_wlan_dev_t which is used as global variable of wilc_wlan.c
will be moved into struct wilc.
This patch moves all members of wilc_wlan_dev_t to struct wilc and use wilc
instead of g_wlan. Finally remove wilc_wlan_dev_t and g_wlan.

Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>