ASoC: ti: davinci-mcasp: Add asynchronous mode support

ASoC: ti: davinci-mcasp: Add asynchronous mode support

McASP has dedicated clock & frame sync registers for both transmit
and receive. Currently McASP driver only supports synchronous behavior and
couples both TX & RX settings.

Add logic that enables asynchronous mode via ti,async-mode property. In
async mode, playback & record can be done simultaneously with different
audio configurations (tdm slots, tdm width, audio bit depth).

Note the ability to have different tx/rx DSP formats (i2s, dsp_a, etc.),
while possible in hardware, remains to be a gap as it require changes
to the corresponding machine driver interface.

Existing IIS (sync mode) and DIT mode logic remains mostly unchanged.
Exceptions are IIS mode logic that previously assumed sync mode, which has
now been made aware of the distinction. And shared logic across all modes
also now checks for McASP tx/rx-specific driver attributes. Those
attributes have been populated according to the original extent, ensuring
no divergence in functionality.

Constraints no longer applicable for async mode are skipped.
Clock selection options have also been added to include rx/tx-only clk_ids,
exposing independent configuration via the machine driver as well.

Note that asynchronous mode is not applicable for McASP in DIT mode,
which is a transmitter-only mode to interface w/ self-clocking formats.

Signed-off-by: Sen Wang <sen@ti.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>
Tested-by: Paresh Bhagat <p-bhagat@ti.com>
Link: https://patch.msgid.link/20260203003703.2334443-5-sen@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>