board: axs103 - add maintainer information

Looks like I forgot to add myself as a maintainer for AXS103 defconfig.
Fixing this now.
Signed-off-by: NAlexey Brodkin <abrodkin@synopsys.com>
Cc: Tom Rini <trini@konsulko.com>

board/synopsys/axs101/MAINTAINERS

@@ -4,3 +4,4 @@ S:	Maintained
 F:	board/synopsys/axs101/
 F:	include/configs/axs101.h
 F:	configs/axs101_defconfig
+F:	configs/axs103_defconfig