gummiboot: upgrade to last commit before being removed
This upgrades to version 48 plus the last commits done after that.
Note, that after that, gummiboot is officially dead, so there will
be no more upstream commits after this.
For various reasons, there are still users of gummiboot, so let's base our
work on the latest gummiboot "version".
Signed-off-by: Esben Haabendal <esben@haabendal.dk>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>