fstrim takes mountpoint as argument but the bash completion
was completing it to a device node.
Addresses: http://bugs.debian.org/804833
Reported-by: Ritesh Raj Sarraf <rrs@debian.org>
Signed-off-by: Andreas Henriksson <andreas@fatal.se>
Users who know the short options can just hit the short option instead
of tab, and it's not likely that it would be helpful to present a list
of single character options to users who don't know them, doing so
just unnecessarily trashes the list of suggestions.
Signed-off-by: Ville Skyttä <ville.skytta@iki.fi>
