uio/uio_pci_generic: fix return value changed in refactoring

Commit ef84928c ("uio/uio_pci_generic: use device-managed function
equivalents") was able to simplify various error paths thanks to no
longer having to clean up on the way out. Some error paths were dropped,
others were simplified. In one of those simplifications, the return
value was accidentally changed from -ENODEV to -ENOMEM. Restore the old
return value.

Fixes: ef84928c

 ("uio/uio_pci_generic: use device-managed function equivalents")
Cc: stable <stable@vger.kernel.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Link: https://lore.kernel.org/r/20210422192240.1136373-1-martin.agren@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>