staging: wilc1000: check if device is initialzied before changing vif

staging: wilc1000: check if device is initialzied before changing vif

When killing hostapd, the interface is closed which deinitializes the
device, then change virtual interface is called.
This change checks if the device is initialized before sending the
interface change command to the device

Signed-off-by: Adham Abozaeid <adham.abozaeid@microchip.com>
Link: https://lore.kernel.org/r/20191028184019.31194-1-adham.abozaeid@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>