Add count_usable_erasers which returns the number of well-defined erasers for a chip

It solves one FIXME and consequentially allows to remove a later check
right now, and is used in the upcoming SFDP patch.
Adds a forward declaration of check_block_eraser.

Corresponding to flashrom svn r1358.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
1 file changed