ASoC: dwc: Enable 24 bit sample size in PIO mode

Sample size of 24 bits use in reality 32 bits for storage. We
can safelly enable this sample size and treat the data as
32 bits.

Tested in a x86_64 platform and in ARC AXS101 SDP platform.

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: Mark Brown <broonie@kernel.org>