scripts/getver.sh: treat all commits as local if can't find upstream

scripts/getver.sh: treat all commits as local if can't find upstream

If something goes wrong and script can't find upstream revision it will
return something like:
r2220
which looks like a valid upstream revision 2220. We cant' distinguish it
from e.g. 2200 upstream commits and 20 local ones.

The new format still provides revision number but also points clearly
that is may be not the upstream one:
r0+2220

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: John Crispin < john@phrozen.org>