ima_measurements.sh: Fix exit code condition

Condition is "$? -ne 0", therefore negative if command passed to if.
This was hidden until fix in the next commit.

Fixes: 4c74c7d ("IMA: Read required policy from file")
Signed-off-by: Petr Vorel <[email protected]>

Author: pevik

testcases/kernel/security/integrity/ima/tests/ima_measurements.sh

@@ -94,7 +94,7 @@ test3()
 	sudo -n -u $user sh -c "echo $(cat /proc/uptime) user file > $file; cat $file > /dev/null"
 	cd ..
 
-	if tst_rod "$cmd" 2> /dev/null; then
+	if ! tst_rod "$cmd" 2> /dev/null; then
 		tst_res TPASS "$cmd failed as expected"
 	else
 		tst_res $IMA_FAIL "$cmd passed unexpectedly"