load ixp42x NPE firmware from separate flash block, remove dead code

Hi,

the following patch adds support to move the IXP42X NPE firmware to a
separate flash block, whose start address is defined in
CONFIG_IXP4XX_NPE_EXT_UCODE_BASE. Using that, it is possible to build
NPE-enabled u-boot without copyright problems due to the NPE firmware.

I hope the patch applies, I get whitespace-related differences in the NPE
files due to trailing whitespace in the original versions.

Signed-off-by: Michael Schwingen <michael@schwingen.org>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>