PCI: endpoint: pci-epf-vntb: Return -ENOENT if pci_epc_get_next_free_bar() fails

PCI: endpoint: pci-epf-vntb: Return -ENOENT if pci_epc_get_next_free_bar() fails

According the function documentation of epf_ntb_init_epc_bar(), the
function should return an error code on error. However, it returns -1 when
no BAR is available i.e., when pci_epc_get_next_free_bar() fails.

Return -ENOENT instead.

Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
[mani: changed err code to -ENOENT]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20250603-pci-vntb-bar-mapping-v2-1-fc685a22ad28@baylibre.com