Revert "ASoC: fsl_sai: replace regmap_write with regmap_update_bits"

This reverts commit 30b14a93 which is
commit 0e270f32 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Iee8d89d7065fa23b5cfb0391ca3a9ba5264263ff
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>