i.MX6: Correct ANATOP_PFD (Phase Fractional Divider) register declarations

i.MX6: Correct ANATOP_PFD (Phase Fractional Divider) register declarations

Some _CLKGATE_MASK and _FRAC_MASK macros were wrong for PFD_480
and the PFD_528 macros were missing.

Fortunately, the incorrect macros weren't being used.

Since both the PFD_480 and PFD_528 registers have the same
structure, and the fields are identical for [0..3] in bytes
[0..3], so a single set of macros will suffice.

Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>