staging: lustre: mdc: Report D_CHANGELOG messages as D_HSM

Removed the D_CHANGELOG pseudo-debug flag that wasn't actually defined
as a usable one. Report the D_CHANGELOG messages as D_HSM ones instead
since this is the primary user of these messages.

Signed-off-by: Henri Doreau <henri.doreau@cea.fr>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5538
Reviewed-on: http://review.whamcloud.com/11558


Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>