wl1271: Release interrupt *after* releasing the driver context

The current order causes driver releasing to fail in various ways, and causes
possible instability.

Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>