MAINTAINERS: add entry for FPGA DFL drivers

Add entry for FPGA Device Feature List (DFL) drivers.

Signed-off-by: Wu Hao <[e-mail]>
Acked-by: Alan Tull <[e-mail]>
Acked-by: Moritz Fischer <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

MAINTAINERS

···
 F:	include/linux/fpga/
 W:	http://www.rocketboards.org
 
+FPGA DFL DRIVERS
+M:	Wu Hao <[e-mail]>
+L:	[e-mail]
+S:	Maintained
+F:	Documentation/fpga/dfl.txt
+F:	include/uapi/linux/fpga-dfl.h
+F:	drivers/fpga/dfl*
+
 FPU EMULATOR
 M:	Bill Metzenthen <[e-mail]>
 W:	http://floatingpoint.sourceforge.net/emulator/index.html