lib/tst_test.c: fix error message for zero tcnt

Remove the word "not".

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
diff --git a/lib/tst_test.c b/lib/tst_test.c
index 7dd890b..ba5eab0 100644
--- a/lib/tst_test.c
+++ b/lib/tst_test.c
@@ -698,7 +698,7 @@
 		tst_brk(TBROK, "You can define only one test function");
 
 	if (tst_test->test && !tst_test->tcnt)
-		tst_brk(TBROK, "Number of tests (tcnt) must not be > 0");
+		tst_brk(TBROK, "Number of tests (tcnt) must be > 0");
 
 	if (!tst_test->test && tst_test->tcnt)
 		tst_brk(TBROK, "You can define tcnt only for test()");