mtd: fix M29W800D dev_id and uaddr

This one sits in my tree for more than two years...
Using device code found on page 12 (http://www.btdesigner.com/pdfs/M29W800D.pdf

)
and unlock address from page 15 MTD subsytem happily detects ST M29W800DB
in 16-bit mode. I do believe original author used only 8-bit mode and thus
didn't hit this bug.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>