PCI: iproc: Drop error data fabrication when config read fails

PCI: iproc: Drop error data fabrication when config read fails

If config pci_ops.read() methods return failure, the PCI_OP_READ() and
PCI_USER_READ_CONFIG() wrappers use PCI_SET_ERROR_RESPONSE() to set the
data value, so there's no need to set it in the pci_ops.read() methods
themselves.

Drop the unnecessary data value fabrication when pci_ops.read() fails.

Link: https://lore.kernel.org/r/b95defa3db834789a4207df5d6b0216c8b610524.1637243717.git.naveennaidu479@gmail.com
Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>