mtd: cfi_cmdset_0001.c: add support for Sharp LH28F640BF NOR

This family of chips was long ago supported by the pre-cfi driver.
CFI code tested on several Zaurus SL-5500 (Collie) 2x16 on 32 bit bus.

Function is_LH28F640BF() mimics is_m29ew() from cmdset_0002.c

Buffer write fixes as seen in 2007 patch c/o
Anti Sullin <anti.sullin <at> artecdesign.ee>
http://comments.gmane.org/gmane.linux.ports.arm.kernel/36733



[Brian: this patch is semi-urgent, because the following patch switches
  to using CFI detection for a chip which (until now) is unsupported by
  the CFI driver

  92183103  ARM: 8084/1: sa1100: collie: revert back to cfi_probe
]

Signed-off-by: Andrea Adami <andrea.adami@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>