MAINTAINERS: add MICROCHIP_FLEXCOM to at91

Add microchip flexcom driver to at91.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index a7c355c..eb24f81 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -246,6 +246,7 @@
 T:	git https://gitlab.denx.de/u-boot/custodians/u-boot-atmel.git
 F:	arch/arm/mach-at91/
 F:	board/atmel/
+F:	drivers/misc/microchip_flexcom.c
 
 ARM OWL
 M:	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>