power: supply: Add Apple Brick ID power supply type

Apple currently supports three very common USB chargers:
https://www.apple.com/power-adapters/

These chargers implement a proprietary Apple method for advertising
1A, 2.1A, and 2.4A at 5V called "Brick ID".
In addition, 3rd parties implement the same charging method in many
charging accessories that work with iOS devices.

Devices that have charger detection chips such as the Pericom PI3USB9281,
eg. Google Chromebook Pixel 2015, are capable of detecting
these chargers, so let's add a type to facilicate passing that info
up to userspace.

This adds a separate power supply type for Apple's proprietary
"Brick ID" charging method.
Signed-off-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

drivers/power/supply/power_supply_sysfs.c

@@ -46,7 +46,7 @@ static ssize_t power_supply_show_property(struct device *dev,
 	static char *type_text[] = {
 		"Unknown", "Battery", "UPS", "Mains", "USB",
 		"USB_DCP", "USB_CDP", "USB_ACA", "USB_C",
-		"USB_PD", "USB_PD_DRP"
+		"USB_PD", "USB_PD_DRP", "BrickID"
 	};
 	static char *status_text[] = {
 		"Unknown", "Charging", "Discharging", "Not charging", "Full"

include/linux/power_supply.h

@@ -159,13 +159,14 @@ enum power_supply_type {
 	POWER_SUPPLY_TYPE_BATTERY,
 	POWER_SUPPLY_TYPE_UPS,
 	POWER_SUPPLY_TYPE_MAINS,
-	POWER_SUPPLY_TYPE_USB,		/* Standard Downstream Port */
-	POWER_SUPPLY_TYPE_USB_DCP,	/* Dedicated Charging Port */
-	POWER_SUPPLY_TYPE_USB_CDP,	/* Charging Downstream Port */
-	POWER_SUPPLY_TYPE_USB_ACA,	/* Accessory Charger Adapters */
-	POWER_SUPPLY_TYPE_USB_TYPE_C,	/* Type C Port */
-	POWER_SUPPLY_TYPE_USB_PD,	/* Power Delivery Port */
-	POWER_SUPPLY_TYPE_USB_PD_DRP,	/* PD Dual Role Port */
+	POWER_SUPPLY_TYPE_USB,			/* Standard Downstream Port */
+	POWER_SUPPLY_TYPE_USB_DCP,		/* Dedicated Charging Port */
+	POWER_SUPPLY_TYPE_USB_CDP,		/* Charging Downstream Port */
+	POWER_SUPPLY_TYPE_USB_ACA,		/* Accessory Charger Adapters */
+	POWER_SUPPLY_TYPE_USB_TYPE_C,		/* Type C Port */
+	POWER_SUPPLY_TYPE_USB_PD,		/* Power Delivery Port */
+	POWER_SUPPLY_TYPE_USB_PD_DRP,		/* PD Dual Role Port */
+	POWER_SUPPLY_TYPE_APPLE_BRICK_ID,	/* Apple Charging Method */
 };
 
 enum power_supply_notifier_events {