bootctl: don't fail 'status' when the ESP has no random seed

Since f90efd2d13 the result of the
access() check for loader/random-seed is stored in 'r', which is what
verb_status() returns. A missing seed file then makes 'bootctl status'
exit with 1 without logging anything, even though it's only reported as
"Exists: no". Use 'k' for the check, like the other informational
probes in this function.

(cherry picked from commit 05808e11b9399e6c2149f1f524b3282545ba7569)

src/bootctl/bootctl-status.c

@@ -621,11 +621,11 @@ int verb_status(int argc, char *argv[], uintptr_t _data, void *userdata) {
                         if (!p)
                                 return log_oom();
 
-                        r = access(p, F_OK);
-                        if (r < 0 && errno != ENOENT)
+                        k = access(p, F_OK);
+                        if (k < 0 && errno != ENOENT)
                                 printf("       Exists: Can't access %s (%m)\n", p);
                         else
-                                printf("       Exists: %s\n", yes_no(r >= 0));
+                                printf("       Exists: %s\n", yes_no(k >= 0));
                 }
 
                 printf("\n");