ASoC: dwc: Add record capability in PIO mode

Up until now PIO mode offered only playback support. With
this patch we add support for record mode. The PCM was
refactored so that we could reuse the existing infrastructure
without many changes.

We have support for 16 and 32 bits of sample size using
only 2 channels.

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>