ASoC: spacemit: adjust FIFO trigger threshold to half FIFO size

ASoC: spacemit: adjust FIFO trigger threshold to half FIFO size

Set both TX and RX FIFO trigger thresholds (TFT/RFT) to 0xF (half of
the 32-entry FIFO) instead of 5. This provides better DMA efficiency
by allowing more data to accumulate before triggering a DMA request,
reducing the number of DMA transactions needed.

Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Link: https://patch.msgid.link/20260429-k3-i2s-v1-3-2fe99db11ecb@linux.spacemit.com
Signed-off-by: Mark Brown <broonie@kernel.org>