cfi-flash: Add CFG_FLASH_AUTOPROTECT_LIST

cfi-flash: Add CFG_FLASH_AUTOPROTECT_LIST

This patch adds a configurable flash auto protection list that can be used
to make U-Boot protect flash regions in flash_init().

The idea has been discussed on the u-boot mailing list starting
on Nov 18th, 2007.

Even this patch brings a new feature it is used as a bugfix for 4xx
platforms where flash_init() does not completely protect the
monitor's flash range in all situations.

U-Boot protects the flash range from CFG_MONITOR_BASE to
(CFG_MONITOR_BASE + monitor_flash_len  - 1) by default. This does not
include the reset vector at 0xfffffffc.

Example:
#define CFG_FLASH_AUTOPROTECT_LIST {{0xfff80000, 0x80000}}

This config option will auto protect the last 512k of flash that
contains the bootloader on board like APC405 and PMC405.

Signed-off-by: Matthias Fuchs <matthias.fuchs@esd-electronics.com>