dpll: zl3073x: Store raw register values instead of parsed state

dpll: zl3073x: Store raw register values instead of parsed state

The zl3073x_ref, zl3073x_out and zl3073x_synth structures
previously stored state that was parsed from register reads. This
included values like boolean 'enabled' flags, synthesizer selections,
and pre-calculated frequencies.

This commit refactors the state management to store the raw register
values directly in these structures. The various inline helper functions
are updated to parse these raw values on-demand using FIELD_GET.

Reviewed-by: Petr Oros <poros@redhat.com>
Tested-by: Prathosh Satish <Prathosh.Satish@microchip.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Link: https://patch.msgid.link/20251113074105.141379-2-ivecera@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>