Fix for channel reconfiguration case: once the EPOL, POL or PHA has been
configured to 1, further configuration on the channel can't change it to 0.

The first CS enable is not needed. The CS will be enabled right before
the transfer anyway, if it's not active.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>