MAINTAINERS: Add entry for devm helpers

Devm helper header containing small inline helpers was added.
Hans promised to maintain it.

Add Hans as maintainer and myself as designated reviewer.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Link: https://lore.kernel.org/r/eec1797734e3d080662aa732c565ed4a3c261799.1616506559.git.matti.vaittinen@fi.rohmeurope.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -5169,6 +5169,12 @@ M:	Torben Mathiasen <device@lanana.org>
 S:	Maintained
 W:	http://lanana.org/docs/device-list/index.html
 
+DEVICE RESOURCE MANAGEMENT HELPERS
+M:	Hans de Goede <hdegoede@redhat.com>
+R:	Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
+S:	Maintained
+F:	include/linux/devm-helpers.h
+
 DEVICE-MAPPER  (LVM)
 M:	Alasdair Kergon <agk@redhat.com>
 M:	Mike Snitzer <snitzer@redhat.com>