board: samsung: update the MAINTAINERS file

Update the maintainer from Przemyslaw and Lukasz to me.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
diff --git a/board/samsung/smdk5420/MAINTAINERS b/board/samsung/smdk5420/MAINTAINERS
index 0361657..590a114 100644
--- a/board/samsung/smdk5420/MAINTAINERS
+++ b/board/samsung/smdk5420/MAINTAINERS
@@ -10,7 +10,7 @@
 F:	configs/peach-pi_defconfig
 
 ODROID-XU3 BOARD
-M:	Przemyslaw Marczak <p.marczak@samsung.com>
+M:	Jaehoon Chung <jh80.chung@samsung.com>
 S:	Maintained
 F:	board/samsung/smdk5420/
 F:	include/configs/odroid_xu3.h