MAINTAINERS: Add missing regulator regex for Wolfson Arizona parts

The maintainers entry for the Wolfson parts seems to be missing
an entry that covers the Arizona regulator drivers, correct this by
adding one.
Signed-off-by: NCharles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

MAINTAINERS

@@ -13119,6 +13119,7 @@ F:	drivers/mfd/cs47l24*
 F:	drivers/power/supply/wm83*.c
 F:	drivers/rtc/rtc-wm83*.c
 F:	drivers/regulator/wm8*.c
+F:	drivers/regulator/arizona*
 F:	drivers/video/backlight/wm83*_bl.c
 F:	drivers/watchdog/wm83*_wdt.c
 F:	include/linux/mfd/arizona/