perf tests trace+probe_vfs_getname: Fix shellcheck warnings about word splitting...

perf tests trace+probe_vfs_getname: Fix shellcheck warnings about word splitting/quoting

Running shellcheck -S on probe_vfs_getname.sh, throws below warnings:

Before fix:

$ shellcheck -S warning trace+probe_vfs_getname.sh

	In trace+probe_vfs_getname.sh line 13:
	. $(dirname $0)/lib/probe.sh
	  ^-----------^ SC2046 (warning): Quote this to prevent word splitting.

	In trace+probe_vfs_getname.sh line 18:
	. $(dirname $0)/lib/probe_vfs_getname.sh
	  ^-----------^ SC2046 (warning): Quote this to prevent word splitting.

	In trace+probe_vfs_getname.sh line 21:
		evts=$(echo $(perf list syscalls:sys_enter_open* 2>/dev/null | grep -E 'open(at)? ' | sed -r 's/.*sys_enter_([a-z]+) +\[.*$/\1/') | sed 's/ /,/')
		            ^-- SC2046 (warning): Quote this to prevent word splitting.

Fix the shellcheck warnings by adding quotes to prevent word splitting.

Signed-off-by: Akanksha J N <akanksha@linux.ibm.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Disha Goel <disgoel@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
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/20230709182800.53002-2-atrajeev@linux.vnet.ibm.com
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>