mtd: cfi_flash: Fix CFI flash driver for 8-bit bus support

mtd: cfi_flash: Fix CFI flash driver for 8-bit bus support

This commit is based on that patch from aaron.williams@caviumnetworks.com
with same commit title. pulled the same code changes into current u-boot tree.

http://patchwork.ozlabs.org/patch/140863/
http://lists.denx.de/pipermail/u-boot/2011-April/089606.html

This patch corrects the addresses used when working with Spansion/AMD FLASH chips.
Addressing for 8 and 16 bits is almost identical except in the 16-bit case the
LSB of the address is always 0.  The confusion arose because the addresses
in the datasheet for 16-bit mode are word addresses but this code assumed it was
byte addresses.

I have only been able to test this on our Octeon boards which use either an 8-bit
or 16-bit bus.  I have not tested the case where there's an 8-bit part on a 16-bit
bus.

This patch also adds some delays as suggested by Spansion.

If a part can be both 8 and 16-bits, it forces it to work in 8-bit mode if an
8-bit bus is detected.

Apart from the pulled changes, fixed few minor code cleanups and tested
on 256M29EW, 512M29EW flashes.

Before this fix:
---------------
Bank # 1: CFI conformant flash (8 x 8)  Size: 64 MB in 512 Sectors
  AMD Standard command set, Manufacturer ID: 0xFF, Device ID: 0xFF
  Erase timeout: 4096 ms, write timeout: 2 ms
  Buffer write timeout: 5 ms, buffer size: 1024 bytes

After this fix:
--------------
Bank # 1: CFI conformant flash (8 x 8)  Size: 64 MB in 512 Sectors
  AMD Standard command set, Manufacturer ID: 0x89, Device ID: 0x7E2301
  Erase timeout: 4096 ms, write timeout: 2 ms
  Buffer write timeout: 5 ms, buffer size: 1024 bytes

Signed-off-by: Aaron Williams <aaron.williams@caviumnetworks.com>
Signed-off-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
Tested-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>