Add 'tensor' bit to commit_if and writeback_if

For use in the asynchronous tensor instruction.  When 1'b1, sets/unsets
the inuse_tensor status bit in the scoreboard to signal
kickoff/completion of the asynchronous tensor op.

hw/rtl/interfaces/VX_commit_if.sv

@@ -26,6 +26,7 @@ interface VX_commit_if #(
         logic                       wb;
         logic [`NR_BITS-1:0]        rd;
         logic [NUM_LANES-1:0][`XLEN-1:0] data;
+        logic                       tensor;
         logic [PID_WIDTH-1:0]       pid;
         logic                       sop;
         logic                       eop;