mtd, cfi: read AMD 3-byte (expanded) device ids on 16bit devices

mtd, cfi: read AMD 3-byte (expanded) device ids on 16bit devices

tested on the a4m072 board with a S29GL512P flash.

flinfo without this patch
Bank # 1: CFI conformant flash (16 x 16)  Size: 32 MB in 256 Sectors
  AMD Standard command set, Manufacturer ID: 0x01, Device ID: 0x227E
  Erase timeout: 16384 ms, write timeout: 2 ms
  Buffer write timeout: 5 ms, buffer size: 32 bytes
[...]

flinfo with this patch
Bank # 1: CFI conformant flash (16 x 16)  Size: 32 MB in 256 Sectors
  AMD Standard command set, Manufacturer ID: 0x01, Device ID: 0x227E2301
  Erase timeout: 16384 ms, write timeout: 2 ms
  Buffer write timeout: 5 ms, buffer size: 32 bytes
[...]

Signed-off-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>