lightnvm: fix checkpatch terse errors

A couple of small checkpatch fixups to stop it from complaining.

./drivers/lightnvm/core.c:360: WARNING: line over 80 characters
./drivers/lightnvm/core.c:360: ERROR: trailing statements should be on
next line
./drivers/lightnvm/core.c:503: WARNING: Block comments use a trailing */
on a separate line

Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>