perf tests lib probe_vfs_getname: Fix shellcheck warnings about missing shebang/local variables

Running shellcheck on probe_vfs_getname fails with below
warning:

   In ./tools/perf/tests/shell/lib/probe_vfs_getname.sh line 1:
   # Arnaldo Carvalho de Melo <acme@kernel.org>, 2017
   ^-- SC2148 (error): Tips depend on target shell and yours is unknown. Add a shebang or a 'shell' directive.

   In ./tools/perf/tests/shell/lib/probe_vfs_getname.sh line 14:
   	   local verbose=$1
           ^-----------^ SC3043 (warning): In POSIX sh, 'local' is undefined.

Fix this:
  - by adding shebang in the beginning of the file and
  - rename variable verbose to "add_probe_verbose" after removing
    local

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Disha Goel <disgoel@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230709182800.53002-19-atrajeev@linux.vnet.ibm.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>