Ensure K value in reverseK is at least 1

Passing 0 or a negative value for K does not cause errors, as the input
is an integer. However, this behavior may be confusing for users. To
improve clarity, enforce K to be an integer greater than or equal to 1
and return an error if the input is invalid.

Co-authored-by: Po-Ying Chiu <charlie910417@gmail.com>
Change-Id: I6741888f888523d00f83cd554fc1442e99120a64

Author: EricccTaiwan

qtest.c

@@ -823,8 +823,8 @@ static bool do_reverseK(int argc, char *argv[])
     error_check();
 
     if (argc == 2) {
-        if (!get_int(argv[1], &k)) {
-            report(1, "Invalid number of K");
+        if (!get_int(argv[1], &k) || k < 1) {
+            report(1, "Invalid number of K (at least 1)");
             return false;
         }
     } else {