ASoC: fsl_sai: fix Rx synchrounous mode

When using the Rx clock for both, transmitter and receiver, the
transmitter needs to be set to synchronous with receiver.

This reverts 855675f6

 ("ASoC: fsl_sai: Set SYNC bit of TCR2 to
Asynchronous Mode"), which, judiging from the commit log, seems to
mixed up between the two synchronous modes: The boolean
sai->synchronous[TX] is indicating wheather the SAI should work in
Rx synchronous mode (sync Tx with Rx), hence if the value is true,
the SYNC field of TCR2 needs to be set to 0x1 ("Synchronous with
receiver").

Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>