firmware: xilinx: Add OSPI Mux selection support

Add OSPI Mux selection API support to select the AXI interface to OSPI.

Signed-off-by: Sai Krishna Potthuri <lakshmi.sai.krishna.potthuri@xilinx.com>
Link: https://lore.kernel.org/r/1632478031-12242-2-git-send-email-lakshmi.sai.krishna.potthuri@xilinx.com


Signed-off-by: Mark Brown <broonie@kernel.org>