[PATCH] libata: fix pio_mask values (take 2)

ata_get_mode_mask() uses bits 3 and 4 in the pio_mask to represent PIO
modes 3 and 4.  The value read from the drive, which reports support
for PIO3 and PIO4 in bits 0 and 1, is shifted left by 3 bits and OR'd
with 0x7 (which then corresponds to PIO 2-0 in libata).  Thus, the
drivers below need adjustments to comply with the way pio_mask is
used.  I changed the masks from the commented values to all support
PIO4-0, since the spec mandates that PIO0-2 are supported and there's
no reason not to support PIO3 IMO.

Signed-off-by: Brett Russ <russb@emc.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>