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/stm32mp1/MAINTAINERS b/board/engicam/stm32mp1/MAINTAINERS
index 405ff99..4ba2a76 100644
--- a/board/engicam/stm32mp1/MAINTAINERS
+++ b/board/engicam/stm32mp1/MAINTAINERS
@@ -23,4 +23,5 @@
 S:	Maintained
 F:	arch/arm/dts/stm32mp15*icore*
 F:	board/engicam/stm32mp1
+F:	board/engicam/common
 F:	configs/stm32mp15-icore-stm32mp1-edimm2.2_defconfig