PCI: pci-epf-test: Use pci_epc_get_features() to get EPC features

Use pci_epc_get_features() to get EPC features such as linkup
notifier support, MSI/MSIX capable, BAR configuration etc and use it
for configuring pci-epf-test. Since these features are now obtained
directly from EPC driver, remove pci_epf_test_data which was initially
added to have EPC features in endpoint function driver.

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