ARM: Fix warning: #warning syscall migrate_pages not implemented

We're not implementing this syscall (we're not NUMA) so we might as
well silence this warning.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 89f7ead..7020217 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -456,6 +456,7 @@
  * Unimplemented (or alternatively implemented) syscalls
  */
 #define __IGNORE_fadvise64_64		1
+#define __IGNORE_migrate_pages		1
 
 #endif /* __KERNEL__ */
 #endif /* __ASM_ARM_UNISTD_H */