cfi_flash: reverse geometry for newer STM parts

For newer STM parts where CFI >= 1.1, there is a byte in the extended
structure that declares the flash layout type (just like the AMD parts),
so key off of that to find out when we need to reverse the geometry.

This can be seen with M29W640 parts where U-Boot does:
Bank # 1: CFI conformant FLASH (16 x 16)  Size: 8 MB in 135 Sectors
  AMD Standard command set, Manufacturer ID: 0x20, Device ID: 0x22ED
  Erase timeout: 8192 ms, write timeout: 1 ms
  Buffer write timeout: 1 ms, buffer size: 16 bytes

  Sector Start Addresses:
  20000000   RO   20002000   RO   20004000   RO   20006000   RO   20008000   RO
  2000A000   RO   2000C000   RO   2000E000   RO   20010000   RO   20020000   RO
  ...

But Linux does:
physmap platform flash device: 00800000 at 20000000
physmap-flash.0: Found 1 x16 devices at 0x0 in 16-bit bank.
                 Manufacturer ID 0x000020 Chip ID 0x0022ed
physmap-flash.0: Swapping erase regions for top-boot CFI table.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Stefan Roese <sr@denx.de>