staging: wilc1000: fix spelling mistake: "Preamle" -> "Preamble"

Trivial fix to spelling mistake in netdev_err error message

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>