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

tools/perf/tests/shell/lib/probe_vfs_getname.sh

+#!/bin/sh
 # Arnaldo Carvalho de Melo <acme@kernel.org>, 2017
 
 perf probe -l 2>&1 | grep -q probe:vfs_getname
@@ -10,11 +11,11 @@ cleanup_probe_vfs_getname() {
 }
 
 add_probe_vfs_getname() {
-	local verbose=$1
+	add_probe_verbose=$1
 	if [ $had_vfs_getname -eq 1 ] ; then
 		line=$(perf probe -L getname_flags 2>&1 | grep -E 'result.*=.*filename;' | sed -r 's/[[:space:]]+([[:digit:]]+)[[:space:]]+result->uptr.*/\1/')
 		perf probe -q       "vfs_getname=getname_flags:${line} pathname=result->name:string" || \
-		perf probe $verbose "vfs_getname=getname_flags:${line} pathname=filename:ustring"
+		perf probe $add_probe_verbose "vfs_getname=getname_flags:${line} pathname=filename:ustring"
 	fi
 }