patman: Don't allow spaces in tags

patman: Don't allow spaces in tags

At present something like:

   Revert "arm: Add cache operations"

will try to use

   Revert "arm

as a tag. Clearly this is wrong, so fix it.

If the revert is intended to be tagged, then the tag can come before
the revert, perhaps. Alternatively the 'Cc' tag can be used in the commit
messages.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>