board: Remove essentially empty board files and Makefiles

As part of reviewing a new platform, Daniel Schwierzeck noted that we
can have an empty Makefile in the board directory and don't need an
empty board.c file as well.  Further with further cleanup in the
Makefile we can now omit the Makefile entirely. Remove a number of now
unnecessary board.c and Makefiles.

Signed-off-by: Tom Rini <trini@konsulko.com>