MAINTAINERS: Add a number of "common" directories

A number of platforms have "common" directories that are in turn not
listed by the board MAINTAINERS file.  Add these directories in many
cases.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/board/Synology/ds109/MAINTAINERS b/board/Synology/ds109/MAINTAINERS
index 8783fdb..2c50edc 100644
--- a/board/Synology/ds109/MAINTAINERS
+++ b/board/Synology/ds109/MAINTAINERS
@@ -2,5 +2,6 @@
 M:	Walter Schweizer <swwa@users.sourceforge.net>
 S:	Maintained
 F:	board/Synology/ds109
+F:	board/Synology/common
 F:	configs/ds109_defconfig
 F:	include/configs/ds109.h
diff --git a/board/Synology/ds116/MAINTAINERS b/board/Synology/ds116/MAINTAINERS
index a5080b0..8d3cc24 100644
--- a/board/Synology/ds116/MAINTAINERS
+++ b/board/Synology/ds116/MAINTAINERS
@@ -3,5 +3,6 @@
 S:	Maintained
 F:	arch/arm/dts/armada-385-synology-ds116.dts
 F:	board/Synology/ds116/
+F:	board/Synology/common
 F:	include/configs/ds116.h
 F:	configs/ds116_defconfig
diff --git a/board/Synology/ds414/MAINTAINERS b/board/Synology/ds414/MAINTAINERS
index 502cbd7..22b7535 100644
--- a/board/Synology/ds414/MAINTAINERS
+++ b/board/Synology/ds414/MAINTAINERS
@@ -2,5 +2,6 @@
 M:	Phil Sutter <phil@nwl.cc>
 S:	Maintained
 F:	board/Synology/ds414/
+F:	board/Synology/common/
 F:	include/configs/ds414.h
 F:	configs/ds414_defconfig