Reworked version of FS#12402 by Jean-Louis Biasini.
Since the mkimxboot process takes quite a while which blocks the UI it has been
adjusted to perform the actual firmware patching in a separate process. Various
other small changes have been made to make it fit better into Rockbox Utility's
dialogs / messages and update the code to latest changes.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31580 a1c6a512-1295-4272-9138-f99709370657
