obexftp: Fix error reporting on initialization
obexftp: Fix error reporting on initialization

Found by Coverity Scan analysis

cpatulea/gvfs,xkahn/gvfs-cmis,cpatulea/gvfs,philipl/gvfs,xkahn/gvfs-cmis,philipl/gvfs,xkahn/gvfs-cmis,gicmo/gvfs,halfline/gvfs,philipl/gvfs,gicmo/gvfs,halfline/gvfs,xkahn/gvfs-cmis,halfline/gvfs,gicmo/gvfs,gicmo/gvfs