Merge branch '2021-06-08-display-and-logging-updates' into next

Merge branch '2021-06-08-display-and-logging-updates' into next

To quote Simon, first for the display changes:
At present we have two ways of showing a hex dump. Once has been in
U-Boot since the dawn of time and the other was recently added from
Linux.

They both have their own unique features.

This series makes a few changes to bring them closer together. It also
adds support for logging a buffer, which is useful since it can put it
through the same log drivers as other logging output.

Also it adds tests, so we can check the behaviour.

And then the logging changes:
At present when logging is not enabled, all log() calls become nops.
This does not seem right, since if the log level is high enough then
there should be some sort of message. So in that case, this series
updates it to print the message if the log level is above LOGL_INFO.

This mimics the behaviour for the log_...() macros like log_debug() and
log_info(), so we can drop the special case for these.

Also the current implementation does not support multiple log calls on
the same line nicely. The tags are repeated so the line is very hard to
read.  This series adds that as a new feature.