perf tests daemon: Address shellcheck warnings

Running shellcheck -S on daemon.sh throws below warnings:

Result from shellcheck:
     # shellcheck -S warning daemon.sh
     local line_name=`echo "${line}" | awk 'BEGIN { FS = ":" } ; { print $2 }'`
           ^-------^ SC2155: Declare and assign separately to avoid masking return values.

     trap "echo 'FAILED: Signal caught'; daemon_exit ${config}; exit 1" SIGINT SIGTERM
                                                     ^-------^ SC2064: Use single quotes, otherwise this expands now rather than when signalled.

     count=`ls ${base}/session-test/ | grep perf.data | wc -l`
            ^-- SC2010: Don't use ls | grep. Use a glob or a for loop with a condition to allow non-alphanumeric filenames.

     if [ ${size} != "OK" -o ${type} != "OK" ]; then
                          ^-- SC2166: Prefer [ p ] || [ q ] as [ p -o q ] is not well defined.

Fixed above warnings by:
   - declaring and assigning local variables separately
   - To fix SC2010, instead of using "ls | grep", used glob to allow non-alphanumeric filenames
   - Used single quotes to prevent expanding.

Result from shellcheck after patch changes:
     $ shellcheck -S warning daemon.sh
     $ echo $?
       0

Signed-off-by: Shirisha G <shirisha@linux.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/20230613164145.50488-5-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>