Exclude multidimensional interface code from Genus targets

- Current versions of Genus (up to 251) don't support
multidimensional interface arrays. Using the axi package means
that the script generated for synthesis will include the
multidimensional array code and die in the parser if the code is
unused.

Author: uge

src/axi_xbar_unmuxed.sv

@@ -268,7 +268,8 @@ import cf_math_pkg::idx_width;
 endmodule
 
 `ifndef VCS
-// As of now, VCS does not support multi-dimensional array of interfaces.
+`ifndef TARGET_GENUS
+// As of now, VCS and Genus does not support multi-dimensional array of interfaces.
 `include "axi/assign.svh"
 `include "axi/typedef.svh"
 
@@ -350,3 +351,4 @@ import cf_math_pkg::idx_width;
 endmodule
 
 `endif
+`endif