hpt366: fix PCI clock detection for HPT374 (take 4)

HPT374 BIOS seems to only save f_CNT register value for the function #0 before
re-tuning DPLL (that causes the driver to report obviously distorted f_CNT for
the function #1) -- fix this by always reading the saved f_CNT register value
from the function #0 in the driver's init_chipset() method.
While at it, introduce 'chip_type' for holding the 'struct hpt_info' field
of the same name and replace the structure assignment with memcpy()...

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