serial: core: fix console problems on uart_close

Commit 761ed4a94582 ('tty: serial_core: convert uart_close to use
tty_port_close') started setting the ttyport console flag for serial
drivers. This is causing crashes, hangs, or garbage output on several
platforms because the serial shutdown is skipped and IRQs are left
enabled.

Partially revert commit 761ed4a94582 and drop reporting UART tty_ports
as a console leaving the console handling to the serial_core as it was
before.

Fixes: 761ed4a94582ab29 ("tty: serial_core: convert uart_close to use tty_port_close")
Reported-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Reported-by: Mugunthan V N <mugunthanvnm@ti.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/serial_core.c

@@ -2746,8 +2746,6 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
 	uport->cons = drv->cons;
 	uport->minor = drv->tty_driver->minor_start + uport->line;
 
-	port->console = uart_console(uport);
-
 	/*
 	 * If this port is a console, then the spinlock is already
 	 * initialised.