posix/readDir should populate name for DT_UKNOWN (#8240)

In commit a8296445ad we changed the code to handle
some corner cases on ARM and other platforms, this
PR just avoids the return for unknown filetypes
prematurely and let the name be populated appropriately.

This fixes bug for older XFS implementations such as
in Ubuntu 14.04

cmd/posix-list-dir_unix.go

@@ -58,7 +58,6 @@ func parseDirEnt(buf []byte) (consumed int, name string, typ os.FileMode, err er
 		// to handle such files, MinIO is only interested in
 		// files and directories.
 		typ = unexpectedFileMode
-		return
 	}
 
 	nameBuf := (*[unsafe.Sizeof(dirent.Name)]byte)(unsafe.Pointer(&dirent.Name[0]))