PCI: endpoint: Remove the ->remove() callback

epf_test is allocated using devm_kzalloc(). Hence it's not required to
explicitly free it in remove() callback. Since ->remove() callback doesn't
do anything other than freeing epf_test, remove the ->remove() callback.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>