The CMIX bits are bits 12-15 in register 0x0d. This has been checked
against the datasheet and verified on hardware. Until now, the bit for
CMIX1 was written to CMIX0. The CMIX0 bit was written to a reserved bit.
Signed-off-by: Marius Weber <marius.weber@physics.ox.ac.uk>
`sif_sync` must be triggered to apply NCO frequency changes. To achieve per
channel frequency tunability exeeding the range of the DUC, the NCO frequeny must
adjusted. User code will need to trigger `sif_sync` to achieve this.
`sif_sync` can only be triggered if the bit was cleared. To avoid this pitfall,
the clearing of `sif_sync` is automated.
Signed-off-by: Marius Weber <marius.weber@physics.ox.ac.uk>
