Devboards.de DBM-SoC1 BOARD: Add S line

This was missing the 'S' line causing a warning from genboardscfg.py

Signed-off-by: Tom Rini <trini@konsulko.com>

board/devboards/dbm-soc1/MAINTAINERS

@@ -1,4 +1,5 @@
 Devboards.de DBM-SoC1 BOARD
 M:	Marek Vasut <marex@denx.de>
+S:	Maintained
 F:	include/configs/socfpga_dbm_soc1.h
 F:	configs/socfpga_dbm_soc1_defconfig