hpt366: fix kernel oops with HPT302N

The driver crashes the kernel on HPT302N chips due to the missing initializer
for 'hpt302n.settings' having been unfortunately overlooked so far. :-<

Much thanks to Mike Mattie for pin-pointing the reason of crash.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>