[MIPS] SMTC: Build fix.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/cevt-r4k.c b/arch/mips/kernel/cevt-r4k.c
index 08b84d4..a915e56 100644
--- a/arch/mips/kernel/cevt-r4k.c
+++ b/arch/mips/kernel/cevt-r4k.c
@@ -10,6 +10,7 @@
 #include <linux/interrupt.h>
 #include <linux/percpu.h>
 
+#include <asm/smtc_ipi.h>
 #include <asm/time.h>
 
 static int mips_next_event(unsigned long delta,