dm: avoid split of quoted strings where possible

[ Upstream commit 2e84fecf ]

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Stable-dep-of: 249bed82 ("dm ioctl: Avoid double-fetch of version")
Signed-off-by: Sasha Levin <sashal@kernel.org>