Nokia RX-51: Enable usbtty serial console by default

Nokia RX-51: Enable usbtty serial console by default

Now when usbtty serial console is fixed in U-Boot enable CONFIG_USB_TTY for
Nokia RX-51 board by default.

Fix also USB product id as U-Boot ignores CONFIG_USBD_PRODUCTID macro and
include U-Boot string into USB product name to indicate usage of U-Boot.

CONFIG_CONSOLE_MUX is already used and U-Boot console is available for
all in/out devices. Therefore there is no need to have separate commands
'run sercon', 'run usbcon' and 'run vgacon', so remove them.

As space for U-Boot is limited to 256kB, enable CONFIG_OPTIMIZE_INLINING
and disable some other unused options so CONFIG_USB_TTY can be enabled.

Nokia RX-51 does not have easily accessible UART serial console so the only
option for easy debugging is to use device's keyboard+screen or this usbtty
serial console over USB.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Acked-by: Pavel Machek <pavel@ucw.cz>