tty: serial: altera_uart: remove early_altera_uart_setup

The function has no users inside the tree and the nios2
(out-of-mainline) port doesn't use it either (anymore).

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>