wl1271: skip 3 unused bytes from the NVS

Our NVS uploading mechanism had a bug that was causing it to pass three extra
zeros at the start of the NVS.  This may be a problem in the NVS generation
application, but for now we fix it in the driver.

Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>