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/emulation/qemu-riscv/MAINTAINERS b/board/emulation/qemu-riscv/MAINTAINERS
index 78969ed..3d7453f 100644
--- a/board/emulation/qemu-riscv/MAINTAINERS
+++ b/board/emulation/qemu-riscv/MAINTAINERS
@@ -2,6 +2,7 @@
 M:	Bin Meng <bmeng.cn@gmail.com>
 S:	Maintained
 F:	board/emulation/qemu-riscv/
+F:	board/emulation/common/
 F:	include/configs/qemu-riscv.h
 F:	configs/qemu-riscv32_defconfig
 F:	configs/qemu-riscv32_smode_defconfig