altera_uart: Add support for getting mapbase and IRQ from resources

This makes it much easier to integrate the driver with the rest of
the Linux (e.g. MFD subsystem).

The old method is still supported though.

Also, from now on, there is one platform device per port (no
changes are needed for the platform code, as no one registers
the devices anywhere in-tree yet).

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>