gluster: Change sp name for hook content read

There's an issue with using same procedure with
different row mappers. The procedure name - row mapper
is cached and causes exception.
So changed code to use different procedure for
getting hook content

Change-Id: Icd3c74bea322edf636fd166eb93785eceec0ed57
Signed-off-by: Sahina Bose <sabose@redhat.com>