mfd: early init for MFD running regulators

For MFDs running regulator cores, we really want them to be brought up early
during boot.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Mike Rapoport <mike@compulab.co.il>
diff --git a/drivers/mfd/wm8400-core.c b/drivers/mfd/wm8400-core.c
index 7c21bf7..ecfc8bb 100644
--- a/drivers/mfd/wm8400-core.c
+++ b/drivers/mfd/wm8400-core.c
@@ -460,7 +460,7 @@
 
 	return ret;
 }
-module_init(wm8400_module_init);
+subsys_initcall(wm8400_module_init);
 
 static void __exit wm8400_module_exit(void)
 {