Support up to 7 banks for ids as specified in JEDEC JEP106Z

see http://www.jedec.org/download/search/jep106Z.pdf


Add some second source legacy flash chips 256x8.

Signed-off-by: Niklaus Giger <niklaus.giger@member.fsf.org>
Signed-off-by: Stefan Roese <sr@denx.de>