ASoC: topology: Add missing clock gating parameter when parsing hw_configs

Clock gating parameter is a part of `dai_fmt`. It is supported by
`alsa-lib` when creating a topology binary file, but ignored by kernel
when loading this topology file.

After applying this commit, the clock gating parameter is not ignored any
more. This solution is backwards compatible. The existing behaviour is
not broken, because by default the parameter value is 0 and is ignored.

snd_soc_tplg_hw_config.clock_gated = 0 => no effect
snd_soc_tplg_hw_config.clock_gated = 1 => SND_SOC_DAIFMT_GATED
snd_soc_tplg_hw_config.clock_gated = 2 => SND_SOC_DAIFMT_CONT

For example, the following config, based on
alsa-lib/src/conf/topology/broadwell/broadwell.conf, is now supported:

~~~~
SectionHWConfig."CodecHWConfig" {
        id "1"
        format "I2S"            # physical audio format.
        pm_gate_clocks "true"   # clock can be gated
}

SectionLink."Codec" {

        # used for binding to the physical link
        id "0"

        hw_configs [
                "CodecHWConfig"
        ]

        default_hw_conf_id "1"
}
~~~~

Signed-off-by: Kirill Marinushkin <k.marinushkin@gmail.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Mark Brown <broonie@kernel.org>
Cc: Pan Xiuli <xiuli.pan@linux.intel.com>
Cc: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Cc: linux-kernel@vger.kernel.org
Cc: alsa-devel@alsa-project.org
Signed-off-by: Mark Brown <broonie@kernel.org>