ARM: dts: imx7d-sdb: Add nodes for audio sound card

Configure the SAI device node, configure audio clock
and pinctrl.

Enable the audio sound card, which use the SAI1 and
wm8960, and enable headphone detection.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>