dm: remove unlikely() before IS_ERR()

IS_ERR() already contains an 'unlikely' compiler flag so there is no
need to do that again from IS_ERR() callers.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --cc drivers/md/dm-snap-persistent.c
Simple merge

diff --cc drivers/md/dm-verity.c
Simple merge

diff --cc drivers/md/persistent-data/dm-block-manager.c
Simple merge