dm init: remove trailing newline from calls to DMERR() and DMINFO()

These printing macros already add a trailing newline, so having another
one here just makes for blank lines when these prints are enabled.
Remove these needless newlines.

Fixes: 6bbc923d

 ("dm: add support to directly boot to a mapped device")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>