ASoC: SPEAr spdif_in: Add spdif IN support

This patch implements the spdif IN driver for ST peripheral

Signed-off-by: Vipin Kumar <vipin.kumar@st.com>
Signed-off-by: Rajeev Kumar <rajeev-dlh.kumar@st.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>