pmic: axp: define ALDO_IN startup bit

Most AXP PMICs feature a "startup source" register, which keeps
information about how the PMIC started operation. Bit 0 in there means
it has been started by "plugging in the power cable".

Define a symbol in each PMIC's header file to be able to use that
register and bit later on.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/include/axp305.h b/include/axp305.h
index 225c504..0a42bc6 100644
--- a/include/axp305.h
+++ b/include/axp305.h
@@ -15,3 +15,6 @@
 #define AXP305_OUTPUT_CTRL1_DCDCD_EN	(1 << 3)
 
 #define AXP305_POWEROFF			(1 << 7)
+
+#define AXP_POWER_STATUS		0x00
+#define AXP_POWER_STATUS_ALDO_IN		BIT(0)