ASoC: fsl_spdif: spba clk is needed by spdif device

SPDIF need to enable the spba clock, when sdma is using share peripheral
script. In this case, there is two spba master port is used, if don't
enable the clock, the spba bus will have arbitration issue, which may
cause read/write wrong data from/to SPDIF registers.

Signed-off-by: Shengjiu Wang <shengjiu.wang@freescale.com>
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>