tensor: Write stall logic for hgmma_wait

HGMMA_WAIT instruction stalls at issue when inuse_tensor is set, which
is done by the previous HGMMA insn. Currently inuse_tensor is never set
back to zero.

hw/rtl/core/VX_decode.sv

@@ -543,6 +543,16 @@ module VX_decode  #(
             end
         `ifdef EXT_T_ENABLE
             `INST_EXT4: begin
+            `ifdef EXT_T_HOPPER
+                ex_type = `EX_TENSOR;
+                // tensor core macroop is encoded as r-type
+                if (func3[0]) begin
+                    op_type = `INST_TENSOR_HGMMA_WAIT;
+                end else begin
+                    op_type = `INST_TENSOR_HGMMA;
+                end
+                // rd/rs1/rs2/rs3 unused
+            `else
                 ex_type = `EX_TENSOR;
                 op_type = `INST_TENSOR_HMMA;
                 // tensor core macroop is encoded as r-type
@@ -551,6 +561,7 @@ module VX_decode  #(
                 `USED_IREG (rs1);
                 `USED_IREG (rs2);
                 `USED_IREG (rs3);
+            `endif
             end
         `endif
             default:;