axi_i2s/axi_spdif: Remove manual creation of Streaming AXI bus

It looks like Vivado is now able to infer these buses from the sources.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
scripts/adi_ip: Add helper function to create bus clock and reset interface

Add a helper function that can be used to register a clock and a reset interface for the clock and reset signals of a bus.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
axi_i2s/axi_spdif: Create clock and reset interface for DMA bus

This avoids some critical warnings from Vivado that the DMA bus does not has any associated clocks.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>