mod_ssl: log revoked certificates at level INFO

instead of DEBUG.

PR 52162

Partial backport of r1165056 from trunk/2.4.x.

Submitted by: sf
Backported by: rjung
Reviewed by: wrowe, rpluem


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1446637 13f79535-47bb-0310-9956-ffa450edef68