perf test shell probe_vfs_getname: Remove extraneous '=' from probe line number regex

perf test shell probe_vfs_getname: Remove extraneous '=' from probe line number regex

Thomas reported the vfs_getname perf tests failing on s/390, it seems it
was just to some extraneous '=' somehow getting into the regexp, remove
it, now:

  root@x1:~# perf test getname
   91: Add vfs_getname probe to get syscall args filenames             : Ok
   93: Use vfs_getname probe to get syscall args filenames             : FAILED!
  126: Check open filename arg using perf trace + vfs_getname          : Ok
  root@x1:~#

Second one remains a mistery, have to take some time to nail it down.

Reported-by: Thomas Richter <tmricht@linux.ibm.com>
Tested-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Vasily Gorbik <gor@linux.ibm.com>,
Link: https://lore.kernel.org/lkml/1d7f3b7b-9edc-4d90-955c-9345428563f1@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>