MAINTAINERS: Add entry for X-Powers AXP family PMIC drivers

Add an entry for X-Powers AXP family PMIC drivers and list myself
as maintainer.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

MAINTAINERS

@@ -12150,6 +12150,12 @@ F:	include/linux/workqueue.h
 F:	kernel/workqueue.c
 F:	Documentation/workqueue.txt
 
+X-POWERS MULTIFUNCTION PMIC DEVICE DRIVERS
+M:	Chen-Yu Tsai <wens@csie.org>
+L:	linux-kernel@vger.kernel.org
+S:	Maintained
+N:	axp[128]
+
 X.25 NETWORK LAYER
 M:	Andrew Hendry <andrew.hendry@gmail.com>
 L:	linux-x25@vger.kernel.org