sfc: Correctly initialise reset_method in siena_test_chip()

[ Upstream commit ef492f11efed9a6a1686bf914fb74468df59385c ]

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>