tilegx: Enable ARCH_SUPPORTS_ATOMIC_RMW

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
index 7fcd492..7cca418 100644
--- a/arch/tile/Kconfig
+++ b/arch/tile/Kconfig
@@ -134,6 +134,7 @@
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
 	select HAVE_ARCH_KGDB
+	select ARCH_SUPPORTS_ATOMIC_RMW
 
 config TILEPRO
 	def_bool !TILEGX