ata: pata_hpt3x2n: pass base DPLL frequency to hpt3x2n_pci_clock()

Currently, the base DPLL frequency is hardcoded in hpt3x2n_pci_clock().
Align with the updated 'pata_hpt37x' driver, where this frequency is a
parameter to hpt37x_pci_clock().

While at it, also do the following to align with the 'pata_hpt37x' driver:
- fix the 'freq' local variable's type;
- remove the 'iobase' local variable;
- extend the comment to the inl() call;
- move the 'total' local variable's declaration.

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>