ltp: Replace 'PASS/FAIL/SKIP' with 'pass/fail/skip' for LAVA friendly parser

LAVA complain 'Bad test result'
Received signal: <TESTCASE> TEST_CASE_ID=openat02 RESULT=SKIP
Bad test result: SKIP
Ref link:
https://lkft.validation.linaro.org/scheduler/job/21959#L13158

Stop using capital string for result, which is invalid in LAVA
so replace it with small letter strings

Change-Id: Ifaf542fcf1b67f6fff57db3c91c49089ee7eaf0a
Signed-off-by: Chase Qi <chase.qi@linaro.org>
Signed-off-by: Naresh Kamboju <naresh.kamboju@linaro.org>
diff --git a/automated/linux/ltp/ltp.sh b/automated/linux/ltp/ltp.sh
index 86a551b..309e171 100755
--- a/automated/linux/ltp/ltp.sh
+++ b/automated/linux/ltp/ltp.sh
@@ -74,7 +74,9 @@
 
 # Parse LTP output
 parse_ltp_output() {
-    grep -E "PASS|FAIL|CONF"  "$1" | awk '{print $1" "$2}' | sed s/CONF/SKIP/  >> "${RESULT_FILE}"
+    grep -E "PASS|FAIL|CONF"  "$1" \
+        | awk '{print $1" "$2}' \
+        | sed 's/PASS/pass/; s/FAIL/fail/; s/CONF/skip/'  >> "${RESULT_FILE}"
 }
 
 # Run LTP test suite