[MIPS] Fix use of ehb instruction for non-R2 configurations.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
index ff7af36..6888cde 100644
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -214,7 +214,7 @@
 	mtc0	t0, CP0_TCCONTEXT
 	xor	t1, t1, t0
 	mtc0	t1, CP0_STATUS
-	ehb
+	_ehb
 #endif /* CONFIG_MIPS_MT_SMTC */
 	CLI
 	move	a0, sp