rtl_sdr: clean up getopt-string

Signed-off-by: Steve Markgraf <steve@steve-m.de>

src/rtl_sdr.c

@@ -122,7 +122,7 @@ int main(int argc, char **argv)
 	uint32_t samp_rate = DEFAULT_SAMPLE_RATE;
 	uint32_t out_block_size = DEFAULT_BUF_LENGTH;
 
-	while ((opt = getopt(argc, argv, "d:f:g:s:b:n:p:S::")) != -1) {
+	while ((opt = getopt(argc, argv, "d:f:g:s:b:n:p:S")) != -1) {
 		switch (opt) {
 		case 'd':
 			dev_index = verbose_device_search(optarg);