include: dt-bindings: mfd: add atmel flexcom include file

Add dt-bindings include file for Atmel Flexcom hardware block.
This file is copied from Linux kernel.
It is used in devicetrees from Linux.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 5e8693f..687c72d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -312,6 +312,7 @@
 F:	board/atmel/
 F:	drivers/cpu/at91_cpu.c
 F:	drivers/misc/microchip_flexcom.c
+F:	include/dt-bindings/mfd/atmel-flexcom.h
 F:	drivers/timer/mchp-pit64b-timer.c
 
 ARM NEXELL S5P4418