The Promise TX4200 is a 4-port SATA controller based on the PDC40519 chip. It
meets the description of the 20319, so just a simple ID needs to be added to
support this hardware. Thanks to Martin Povolný for testing.
Signed-off-by: NDaniel Drake <dsd@gentoo.org>
Signed-off-by: NJeff Garzik <jgarzik@pobox.com>