storage: Improve virStorageBackendFileSystemStop
storage: Improve virStorageBackendFileSystemStop

It's actually not used for DIR pool. So removing the checking.

VenkatDatta/libvirt,emaste/libvirt,shugaoye/libvirt,VenkatDatta/libvirt,trainstack/libvirt,trainstack/libvirt,fabianfreyer/libvirt,crobinso/libvirt,jardasgit/libvirt,crobinso/libvirt,nertpinx/libvirt,olafhering/libvirt,agx/libvirt,zhlcindy/libvirt-1.1.4-maintain,zhlcindy/libvirt-1.1.4-maintain,datto/libvirt,VenkatDatta/libvirt,emaste/libvirt,olafhering/libvirt,cbosdo/libvirt,eskultety/libvirt,iam-TJ/libvirt,emaste/libvirt,andreabolognani/libvirt,jeckersb/libvirt,rlaager/libvirt,nertpinx/libvirt,libvirt/libvirt,iam-TJ/libvirt,jeckersb/libvirt,iam-TJ/libvirt,jfehlig/libvirt,siboulet/libvirt-openvz,siboulet/libvirt-openvz,jardasgit/libvirt,emaste/libvirt,agx/libvirt,nertpinx/libvirt,crobinso/libvirt,datto/libvirt,trainstack/libvirt,shugaoye/libvirt,bjzhang/libvirt,eskultety/libvirt,siboulet/libvirt-openvz,cbosdo/libvirt,siboulet/libvirt-openvz,jfehlig/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,jeckersb/libvirt,libvirt/libvirt,VenkatDatta/libvirt,rlaager/libvirt,zippy2/libvirt,libvirt/libvirt,jeckersb/libvirt,emaste/libvirt,elmarco/libvirt,iam-TJ/libvirt,cbosdo/libvirt,jeckersb/libvirt,siboulet/libvirt-openvz,emaste/libvirt,datto/libvirt,jardasgit/libvirt,zhlcindy/libvirt-1.1.4-maintain,bjzhang/libvirt,iam-TJ/libvirt,trainstack/libvirt,libvirt/libvirt,jardasgit/libvirt,agx/libvirt,datto/libvirt,iam-TJ/libvirt,jeckersb/libvirt,cbosdo/libvirt,olafhering/libvirt,jardasgit/libvirt,cbosdo/libvirt,jfehlig/libvirt,crobinso/libvirt,jfehlig/libvirt,emaste/libvirt,eskultety/libvirt,jeckersb/libvirt,zippy2/libvirt,taget/libvirt,andreabolognani/libvirt,bjzhang/libvirt,taget/libvirt,bjzhang/libvirt,eskultety/libvirt,eskultety/libvirt,andreabolognani/libvirt,datto/libvirt,elmarco/libvirt,nertpinx/libvirt,trainstack/libvirt,taget/libvirt,andreabolognani/libvirt,zippy2/libvirt,bjzhang/libvirt,shugaoye/libvirt,taget/libvirt,olafhering/libvirt,elmarco/libvirt,andreabolognani/libvirt,zhlcindy/libvirt-1.1.4-maintain,agx/libvirt,VenkatDatta/libvirt,iam-TJ/libvirt,trainstack/libvirt,agx/libvirt,rlaager/libvirt,elmarco/libvirt,rlaager/libvirt,elmarco/libvirt,rlaager/libvirt,zippy2/libvirt,taget/libvirt,trainstack/libvirt,fabianfreyer/libvirt,shugaoye/libvirt,shugaoye/libvirt,fabianfreyer/libvirt,fabianfreyer/libvirt,zhlcindy/libvirt-1.1.4-maintain