PCI: endpoint: Fix error handling in epf_ntb_epc_cleanup()

PCI: endpoint: Fix error handling in epf_ntb_epc_cleanup()

There are two issues related to epf_ntb_epc_cleanup():

  1) It should call epf_ntb_config_sspad_bar_clear()
  2) The epf_ntb_bind() function should call epf_ntb_epc_cleanup()
     to cleanup.

I also changed the ordering a bit.  Unwinding should be done in the
mirror order from how they are allocated.

Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP")
Link: https://lore.kernel.org/linux-pci/aaffbe8d-7094-4083-8146-185f4a84e8a1@moroto.mountain
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>