ARM: dts: prima2: add I2S 2ch, 6ch, nodin, mclk groups

we have done that for atlas6 in commit ed36c1a0, 086b8904 etc. here we
do same things for prima2.

Signed-off-by: Rongjun Ying <rongjun.ying@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>