Part of SSI IRQ enable/disable was controlled by SRU (on Gen1)
or CMD (on Gen2). Because of this reason SSI IRQ function was
implemented under src.c. but it is not understandable.
Let's move it to ssi.c
Signed-off-by: NKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: NMark Brown <broonie@kernel.org>