[MIPS] Fix RM9000 wait instruction detection.

Only revisions < 4.0 don't have a functional wait instruction.

From Thomas Koeller (Thomas.Koeller@baslerweb.com).
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/kernel/cpu-probe.c

@@ -135,7 +135,6 @@ static inline void check_wait(void)
 	case CPU_R5000:
 	case CPU_NEVADA:
 	case CPU_RM7000:
-	case CPU_RM9000:
 	case CPU_4KC:
 	case CPU_4KEC:
 	case CPU_4KSC:
@@ -164,6 +163,14 @@ static inline void check_wait(void)
 		} else
 			printk(" unavailable.\n");
 		break;
+	case CPU_RM9000:
+		if ((c->processor_id & 0x00ff) >= 0x40) {
+			cpu_wait = r4k_wait;
+			printk(" available.\n");
+		} else {
+			printk(" unavailable.\n");
+		}
+		break;
 	default:
 		printk(" unavailable.\n");
 		break;