misc: pci_endpoint_test: Add DesignWare EP entry

Add the DesignWare EP device ID entry to pci_endpoint_test driver table.

Allow the device to be recognized and handled by the pci_endpoint_test
driver.

Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>