Add a metadata entry for the AT45DB641E chip. This chip has the same 3-byte
jedec ID as its older cousin the AT45DB642D, but uses a different page size.
The only way to distinguish between the two chips is that the 2D chip has
0 bytes of extended ID info and the new 1E has 1 byte of extended ID. The
actual value of the extended ID byte is all zeroes. In other words, it's
the presence of the extended info that identifies this chip. (Presumably
a future upgrade might define non-zero values for the extended ID byte.)