Remove duplicate calls to svn_pool_clear().  Follow-up to r1546842.

* subversion/libsvn_fs_fs/recovery.c
  (recover_get_largest_revision): Remove duplicate calls to
    svn_pool_clear().

Patch by: Evgeny Kotkov <evgeny.kotkov{_AT_}visualsvn.com>

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1547421 13f79535-47bb-0310-9956-ffa450edef68