This patch suppresses calculation of REFCLK parameters when the REFCLK
source frequency is set to zero, additionally it will consider a source
frequency of zero as the REFCLK being disabled and switch to using the
SYNCCLK.
Reported-by: NKyung Kwee Ryu <Kyung-Kwee.Ryu@wolfsonmicro.com>
Signed-off-by: NCharles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: NMark Brown <broonie@linaro.org>