hw/9pfs: fix error handing in local_ioc_getversion()

v9fs_co_st_gen() expects to see error code in errno, not in return code.

Let's fix this.
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

hw/9pfs/virtio-9p-local.c

@@ -1068,8 +1068,8 @@ err_out:
 static int local_ioc_getversion(FsContext *ctx, V9fsPath *path,
                                 mode_t st_mode, uint64_t *st_gen)
 {
-    int err;
 #ifdef FS_IOC_GETVERSION
+    int err;
     V9fsFidOpenState fid_open;
 
     /*
@@ -1085,10 +1085,11 @@ static int local_ioc_getversion(FsContext *ctx, V9fsPath *path,
     }
     err = ioctl(fid_open.fd, FS_IOC_GETVERSION, st_gen);
     local_close(ctx, &fid_open);
+    return err;
 #else
-    err = -ENOTTY;
+    errno = ENOTTY;
+    return -1;
 #endif
-    return err;
 }
 
 static int local_init(FsContext *ctx)