staging: wilc1000: move perInterface_wlan_t to wilc_vif

perInterface_wlan_t and wilc_vif are all about interface control informations.
We will combine those two structures and maintain as one network interface
control information.
Move all the members of perInterface_wlan_t to wilc_vif and remove the
structure. Rename perInterace_wlan_t to wilc_vif and rename variable name nic
to vif which is proper name for it.

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