altera_uart: Make it possible to use Altera UART and 8250 ports together

This fixes tty name, major and minor numbers. The major number
204 is used across many platform-specific serial drivers, so we
use that.

Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>