Add utility to print all chip names in flashchips.h that are not in flashchips.c.

This allows to list yet unsupported chips easily.

First it tries to find the directory containing the files, then it uses sed to
extract the macro names of chips from flashchips.h, greps for them in
flashchips.c and prints it if it is not found.
If verbose mode is activated by giving at least one additional parameter
it prints the chip ID and comment following the macro definition too.

Signed-off-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>

git-svn-id: svn://coreboot.org/flashrom/trunk@1654 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1