Revert "udev: prepare memory for extra NUL termination for NULSTR"

This reverts commit cd3c8a117c which was
papering over the bug instead of a proper fix made by the previous
commit.

src/udev/udev-rules.c

@@ -1148,9 +1148,7 @@ static int rule_add_line(UdevRuleFile *rule_file, const char *line_str, unsigned
         if (isempty(line_str))
                 return 0;
 
-        /* We use memdup_suffix0() here, since we want to add a second NUL byte to the end, since possibly
-         * some parsers might turn this into a "nulstr", which requires an extra NUL at the end. */
-        line = memdup_suffix0(line_str, strlen(line_str) + 1);
+        line = strdup(line_str);
         if (!line)
                 return log_oom();