wilc1000: use goto labels on error path

Use goto labels on error path for probe functions. This makes code easier
to read. With this introduce also netdev_cleanup and call it where
necessary.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210806081229.721731-2-claudiu.beznea@microchip.com