Like PCS, TX group reads return 0xffffffff. So we need to target each
lane separately if we want to use RMW cycles to update the registers.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>