target/mips: Raise a RI when given fs is n/a from CTC1

Fix to raise a Reserved Instruction exception when given fs is not
available from CTC1.

Backports commit f48a2cb21824217a61ec7be797860a0702e5325c from qemu

qemu/target/mips/op_helper.c

@@ -2617,6 +2617,9 @@ void helper_ctc1(CPUMIPSState *env, target_ulong arg1, uint32_t fs, uint32_t rt)
                (env->active_fpu.fcr31 & ~(env->active_fpu.fcr31_rw_bitmask));
         break;
     default:
+        if (env->insn_flags & ISA_MIPS32R6) {
+            do_raise_exception(env, EXCP_RI, GETPC());
+        }
         return;
     }
     restore_fp_status(env);