xpowers/axp209: Add helper to set voltages from devicetree config

Change-Id: I3ffe225b78f88c3c2d3a15292c43009e69413afb
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/4638
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
diff --git a/src/drivers/xpowers/axp209/axp209.h b/src/drivers/xpowers/axp209/axp209.h
index 1d369f5..c9cdd7e 100644
--- a/src/drivers/xpowers/axp209/axp209.h
+++ b/src/drivers/xpowers/axp209/axp209.h
@@ -6,6 +6,7 @@
  */
 
 #include <types.h>
+#include "chip.h"
 
 #define AXP209_I2C_ADDR (0x68 >> 1)
 
@@ -15,3 +16,5 @@
 enum cb_err axp209_set_ldo2_voltage(u8 bus, u16 millivolts);
 enum cb_err axp209_set_ldo3_voltage(u8 bus, u16 millivolts);
 enum cb_err axp209_set_ldo4_voltage(u8 bus, u16 millivolts);
+enum cb_err axp209_set_voltages(u8 bus, const struct
+				drivers_xpowers_axp209_config *cfg);