[MTD] [NOR] add FUJITSU MBM29F800BA and ST M29F800AB descriptions

Add descriptions for Fujitsu MBM29F800BA and ST M29F800AB flash chips.
Those chips are compatible (except for the ids) with the AMD AM29F800BB.

Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>