allwinner: Return the PMIC to I2C mode after use

This gives the rich OS the flexibility to choose between I2C and RSB
communication. Since a runtime address can only be assigned once after
entering RSB mode, it also lets the rich OS choose any runtime address.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Change-Id: Id49c124c5e925985fc31c0ba38c7fb6c941aafa8
diff --git a/include/drivers/allwinner/axp.h b/include/drivers/allwinner/axp.h
index 9c0035f..222820b 100644
--- a/include/drivers/allwinner/axp.h
+++ b/include/drivers/allwinner/axp.h
@@ -9,6 +9,10 @@
 
 #include <stdint.h>
 
+#define AXP20X_MODE_REG 0x3e
+#define AXP20X_MODE_I2C 0x00
+#define AXP20X_MODE_RSB 0x7c
+
 #define NA 0xff
 
 enum {