ASoC: add snd_soc_of_parse_daifmt() for DeviceTree

This patch adds snd_soc_of_parse_daifmt() and supports below style on DT.

        [prefix]format = "i2c";
        [prefix]clock-gating = "continuous";
        [prefix]bitclock-inversion;
        [prefix]bitclock-master;
        [prefix]frame-master;

Each driver can use specific [prefix]
(ex simple-card,cpu,dai,format = xxx;)

This sample will be
SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_CONT |
SND_SOC_DAIFMT_IB_NF | SND_SOC_DAIFMT_CBM_CFM

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>