DEVELOPERS: add Lothar Felten as contact for BeagleBone defconfigs

Lothar added the beaglebone and beaglebone_qt5 defconfigs, and has
been regularly maintaining them, so it makes sense to have him listed
as a contact for those two defconfigs.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Lothar Felten <lothar.felten@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

DEVELOPERS

@@ -1431,7 +1431,10 @@ F:	package/mongrel2/
 
 N:	Lothar Felten <lothar.felten@gmail.com>
 F:	board/bananapi/bananapi-m2-ultra/
+F:	board/beaglebone/
 F:	configs/bananapi_m2_ultra_defconfig
+F:	configs/beaglebone_defconfig
+F:	configs/beaglebone_qt5_defconfig
 F:	package/ti-sgx-demos/
 F:	package/ti-sgx-libgbm/
 F:	package/ti-sgx-km/