ASoC: rcar: ssi: don't set SSICR.CKDV = 000 with SSIWSR.CONT

R-Car Datasheet is indicating "SSICR.CKDV = 000 is invalid when
SSIWSR.WS_MODE = 1 or SSIWSR.CONT = 1".
Current driver will set CONT, thus, we shouldn't use CKDV = 000.
This patch fixup it.

Reported-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>