Replace pci_epc_mem_free_addr() with pci_epf_free_space() in the
error handle path to match pci_epf_alloc_space().

Link: https://lore.kernel.org/r/20221102141014.1025893-4-Frank.Li@nxp.com
Fixes: e35f56bb ("PCI: endpoint: Support NTB transfer between RC and EP")
Signed-off-by: NFrank Li <frank.li@nxp.com>
Signed-off-by: NLorenzo Pieralisi <lpieralisi@kernel.org>