gianfar: fix obviously wrong #ifdef CONFIG_GFAR_NAPI placement

Erroneous #ifdef introduced by 293c8513
causing NAPI-less ethernet malfunctioning.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Vitaly Bordug <vbordug@ru.mvista.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>