staging: greybus: uart: fix invalid user-pointer check

Drop invalid user-pointer check from TIOCGSERIAL handler.

A NULL-pointer can be valid in user space and copy_to_user() takes care
of sanity checking.
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/uart.c

@@ -623,9 +623,6 @@ static int get_serial_info(struct gb_tty *gb_tty,
 {
 	struct serial_struct tmp;
 
-	if (!info)
-		return -EINVAL;
-
 	memset(&tmp, 0, sizeof(tmp));
 	tmp.flags = ASYNC_LOW_LATENCY | ASYNC_SKIP_TEST;
 	tmp.type = PORT_16550A;