arc: axs10x: Add DT bindings for I2S audio playback

This patch adds the necessary DT bindings to get HDMI audio
output in ARC AXS10x SDP. The bindings for I2S controller were
added as well as the bindings for simple audio card.

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Cc: Carlos Palminha <palminha@synopsys.com>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: devicetree@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>