Revert "RISC-V: Enable assert for insn_has_dfa_reservation"

This reverts commit 23cd2961bd.

gcc/config/riscv/riscv.cc

@@ -8234,7 +8234,9 @@ riscv_sched_variable_issue (FILE *, int, rtx_insn *insn, int more)
 
   /* If we ever encounter an insn without an insn reservation, trip
      an assert so we can find and fix this problem.  */
+#if 0
   gcc_assert (insn_has_dfa_reservation_p (insn));
+#endif
 
   return more - 1;
 }