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/imx8mp/MAINTAINERS b/board/engicam/imx8mp/MAINTAINERS
index a25908a..c86f9bc 100644
--- a/board/engicam/imx8mp/MAINTAINERS
+++ b/board/engicam/imx8mp/MAINTAINERS
@@ -3,5 +3,6 @@
 M:	Matteo Lisi <matteo.lisi@engicam.com>
 S:	Maintained
 F:	board/engicam/imx8mp
+F:	board/engicam/common
 F:	include/configs/imx8mp_icore_mx8mp.h
 F:	configs/imx8mp-icore-mx8mp-edimm2.2_defconfig