[MIPS] IP22: Enable -Werror.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/sgi-ip22/Makefile b/arch/mips/sgi-ip22/Makefile
index 1fb3e35..e3acb51 100644
--- a/arch/mips/sgi-ip22/Makefile
+++ b/arch/mips/sgi-ip22/Makefile
@@ -7,3 +7,5 @@
 	   ip22-time.o ip22-nvram.o ip22-platform.o ip22-reset.o ip22-setup.o
 
 obj-$(CONFIG_EISA)	+= ip22-eisa.o
+
+EXTRA_CFLAGS += -Werror