dmerror: export configuration so that subprograms don't have to reinit

dmerror: export configuration so that subprograms don't have to reinit

Export the dmerror configuration variables so that subprograms don't
have to reinitialize the configuration in their own subprograms before
calling the helpers.  In the next patch (where we allow dmerror for log
and rt devices) it will become important to avoid these
reinitializations.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>