greybus: uart: fix double free of tty port

When inserting and removing a module with a UART protocol defined a
double free of the tty_port would happen and that would generate a lot
of kernel oops in different places related to memory corruption.
Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/uart.c

@@ -701,7 +701,6 @@ static void gb_uart_connection_exit(struct gb_connection *connection)
 
 	/* FIXME - free transmit / receive buffers */
 
-	tty_port_put(&gb_tty->port);
 	tty_port_destroy(&gb_tty->port);
 	kfree(gb_tty->buffer);
 	kfree(gb_tty);