xfsprogs: add missing line feeds in libxfs/rdwr.c

xfsprogs: add missing line feeds in libxfs/rdwr.c

In libxfs/rdwr.c, there are several fprintf() calls that are
missing trailing line feeds. This translates to the following
CLI prompt being on the same line as the message. Add missing
line feeds, alleviating the issue.

Fixes: 0a7942b38215 ("libxfs: don't discard dirty buffers")
Signed-off-by: John Pittman <jpittman@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>