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/engicam/imx6q/MAINTAINERS b/board/engicam/imx6q/MAINTAINERS
index 6b46378..266da95 100644
--- a/board/engicam/imx6q/MAINTAINERS
+++ b/board/engicam/imx6q/MAINTAINERS
@@ -2,6 +2,7 @@
 M:	Jagan Teki <jagan@amarulasolutions.com>
 S:	Maintained
 F:	board/engicam/imx6q
+F:	board/engicam/common
 F:	include/configs/imx6-engicam.h
 F:	configs/imx6qdl_icore_mmc_defconfig
 F:	configs/imx6q_icore_nand_defconfig