iscsi_direct: Don't overwrite error in virStorageBackenISCSIDirectWipeVol()
iscsi_direct: Don't overwrite error in virStorageBackenISCSIDirectWipeVol()

If virStorageBackendISCSIDirectVolWipeZero() fails, it has
already reported an error which is probably specific enough. Do
not overwrite it with some generic one.

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>
Reviewed-by: Pavel Hrdina <d4772d05997b8abf035041e3b4f4996380ea7e7a@redhat.com>

fabianfreyer/libvirt,nertpinx/libvirt,olafhering/libvirt,crobinso/libvirt,eskultety/libvirt,jardasgit/libvirt,libvirt/libvirt,jfehlig/libvirt,jfehlig/libvirt,eskultety/libvirt,jardasgit/libvirt,crobinso/libvirt,olafhering/libvirt,zippy2/libvirt,jfehlig/libvirt,andreabolognani/libvirt,jardasgit/libvirt,andreabolognani/libvirt,nertpinx/libvirt,jfehlig/libvirt,nertpinx/libvirt,eskultety/libvirt,eskultety/libvirt,fabianfreyer/libvirt,crobinso/libvirt,olafhering/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,jardasgit/libvirt,andreabolognani/libvirt,eskultety/libvirt,crobinso/libvirt,fabianfreyer/libvirt,libvirt/libvirt,libvirt/libvirt,libvirt/libvirt,zippy2/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,nertpinx/libvirt,zippy2/libvirt,andreabolognani/libvirt,olafhering/libvirt,zippy2/libvirt