Fix selfcheck of various arrays.

Stefan Reinauer has reported ridiculous NULL checks for arrays in our
self_check function found by Coverity (CID1130005). This patch removes
the useless checks but keeps and fixes the one responsible for the
flashchips array by exporting the array size in a new constant.

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

git-svn-id: svn://flashrom.org/flashrom/trunk@1799 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1