Removed p as a valid CLI option

The get-socketpath long option had an undocumented short alternative
as `p`. It has been removed.
However, the code in the options array is still the 'p' char.

sway/main.c

@@ -103,7 +103,7 @@ int main(int argc, char **argv) {
 	int c;
 	while (1) {
 		int option_index = 0;
-		c = getopt_long(argc, argv, "hCdvVpc:", long_options, &option_index);
+		c = getopt_long(argc, argv, "hCdvVc:", long_options, &option_index);
 		if (c == -1) {
 			break;
 		}