mboot: add missing Makefiles

And remove Makefile from .gitignore, which was the
problem in the first place.

Bizarre.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>
mboot64: maybe fix the AEM timer.

Can't test since the FM doesn't have the same functionality.

Signed-off-by: Andrei Warkentin <andrey.warkentin@gmail.com>