[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/gdb-low.S b/arch/mips/kernel/gdb-low.S
index 5fd7a8a..8760131 100644
--- a/arch/mips/kernel/gdb-low.S
+++ b/arch/mips/kernel/gdb-low.S
@@ -291,7 +291,7 @@
 		ori	t1, t2, TCSTATUS_IXMT
 		mtc0	t1, CP0_TCSTATUS
 		andi	t2, t2, TCSTATUS_IXMT
-		ehb
+		_ehb
 		DMT	9				# dmt	t1
 		jal	mips_ihb
 		nop
@@ -310,7 +310,7 @@
 		xori	t1, t1, TCSTATUS_IXMT
 		or	t1, t1, t2
 		mtc0	t1, CP0_TCSTATUS
-		ehb
+		_ehb
 #endif /* CONFIG_MIPS_MT_SMTC */
 		LONG_L	v0, GDB_FR_STATUS(sp)
 		LONG_L	v1, GDB_FR_EPC(sp)