ASoC: fsl_ssi: Rename registers and fields macros

This patch renames CCSR_SSI_xxx to REG_SSI_xxx and SSI_xxx_yyy style.
It also slightly reduces the length of them to save some space.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Tested-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Reviewed-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Acked-by: Timur Tabi <timur@tabi.org>
Signed-off-by: Mark Brown <broonie@kernel.org>