dm: remove symbol export for dm_set_device_limits

There is no need for code other than DM core to use dm_set_device_limits
so remove its EXPORT_SYMBOL_GPL.  Also, cleanup a couple whitespace nits.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

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

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

diff --cc include/linux/device-mapper.h
Simple merge