ASoC: fsl_ssi: AC'97 ops need regmap, clock and cleaning up on failure

AC'97 ops (register read / write) need SSI regmap and clock, so they have
to be set after them.

We also need to set these ops back to NULL if we fail the probe.

Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org