m68k: Enable atomic64_t

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index b5da298..2e3737b 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -7,6 +7,7 @@
 	default y
 	select HAVE_AOUT
 	select HAVE_IDE
+	select GENERIC_ATOMIC64
 
 config MMU
 	bool