perf tests arm_callgraph_fp: Address shellcheck warnings about signal names and adding double quotes for expression

Running shellcheck -S on test_arm_calligraph_fp throws warnings SC2086 and SC3049,

      $shellcheck -S warning tests/shell/test_arm_callgraph_fp.sh
         rm -f $PERF_DATA
            : Double quote to prevent globbing and word splitting.
         trap cleanup_files exit term int
                     : In POSIX sh, using lower/mixed case for signal names is undefined.

After fixing the warnings,

      $shellcheck tests/shell/test_arm_callgraph_fp.sh
      $ echo $?
      0

To address the POSIX shell warnings added changes to convert Lowercase
signal names to uppercase in the script and double quoted the
command substitutions($fix to "$fix") to solve Globbing warnings.

Signed-off-by: Spoorthy S<spoorts2@in.ibm.com>
Cc: Disha Goel <disgoel@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230613164145.50488-4-atrajeev@linux.vnet.ibm.comSigned-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>