[U-Boot] Automatic software updates in U-Boot

[Bartlomiej Sieka]

Hello,

This patch series adds support for automatic software updates from a TFTP
server. First patch introduces some changes in the TFTP timeout handling that
are required by the feature proper, which is contained in the second patch.
Third patch provides minor enhancements to the iminfo output that can become
handy when using the new feature.

Please see newly added doc/README.au_tftp for more details.

Code has been compile-tested on several ppc, arm and mips targets. The feature
itself has been tested on TQM8555 and MPC8555CDS.

Regards,
Bartlomiej Sieka