MAINTAINERS: at91: update entry for at91 boards

Updated the maintainership for the at91 boards.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
diff --git a/board/atmel/sama5d4ek/MAINTAINERS b/board/atmel/sama5d4ek/MAINTAINERS
index afe88dd..f715af6 100644
--- a/board/atmel/sama5d4ek/MAINTAINERS
+++ b/board/atmel/sama5d4ek/MAINTAINERS
@@ -1,5 +1,5 @@
 SAMA5D4EK BOARD
-M:	Bo Shen <voice.shen@atmel.com>
+M:	Eugen Hristev <eugen.hristev@microchip.com>
 S:	Maintained
 F:	board/atmel/sama5d4ek/
 F:	include/configs/sama5d4ek.h