Fix error log level in restore-backup routine

[ling-yun]

When doing backup-restore operation, it needs volume's size is not less than backup's size.
But in backup-restore routine, when volume's size is bigger than backup's size, it logs the
the info of volume's size and backup's size to warn level, which I think it should log the info
to info level.
This bug fix it.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/105093

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/105093
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=4469591c76888bad263662df424c3f266ded8d48
Submitter: Jenkins
Branch: master

commit 4469591c76888bad263662df424c3f266ded8d48
Author: ling-yun <email address hidden>
Date: Mon Jul 7 16:51:24 2014 +0800

    Fix error log level in restore-backup routine

    When doing backup-restore operation, it needs volume's size is not less
    than backup's size.
    But in backup-restore routine, when volume's size is bigger than backup's
    size, it logs the the info of volume's size and backup's size to warn
    level, which I think it should log the info to info level.
    This bug fix it.

    Change-Id: Ic7210e3b018053be7a6f567cd0a7b20d51d403b8
    Closes-Bug: #1338481