am335x, guardian: update the maintainer list

I am leaving Bosch, so replacing myself with Gireesh
Signed-off-by: NMoses Christopher <BollavarapuMoses.Christopher@in.bosch.com>

board/bosch/guardian/MAINTAINERS

 Guardian BOARD
 M:	Sjoerd Simons <sjoerd.simons@collabora.co.uk>
 M:	Govindaraji Sivanantham <Govindaraji.Sivanantham@in.bosch.com>
-M:	Moses Christopher Bollavarapu <BollavarapuMoses.Christopher@in.bosch.com>
+M:	Hiremath Gireesh <Gireesh.Hiremath@in.bosch.com>
 S:	Maintained
 F:	board/bosch/guardian/
 F:	include/configs/am335x_guardian.h