ASoc: Fix unused define in jz4740-i2s.h

Delete unused define of JZ4740_I2S_BIT_CLK, because it is unused
in any files.

Signed-off-by: Zhang Shengju <zhangshengju@cmss.chinamobile.com>
Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20210506131833.27420-1-tangbin@cmss.chinamobile.com


Signed-off-by: Mark Brown <broonie@kernel.org>