hw/9pfs: Use export_flag for indicating whether fs driver use path names.

This allows us to remove another member from the struct

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
diff --git a/hw/9pfs/virtio-9p.h b/hw/9pfs/virtio-9p.h
index e94041e..802f580 100644
--- a/hw/9pfs/virtio-9p.h
+++ b/hw/9pfs/virtio-9p.h
@@ -422,21 +422,21 @@
 
 static inline void v9fs_path_write_lock(V9fsState *s)
 {
-    if (s->ctx.flags & PATHNAME_FSCONTEXT) {
+    if (s->ctx.export_flags & V9FS_PATHNAME_FSCONTEXT) {
         qemu_co_rwlock_wrlock(&s->rename_lock);
     }
 }
 
 static inline void v9fs_path_read_lock(V9fsState *s)
 {
-    if (s->ctx.flags & PATHNAME_FSCONTEXT) {
+    if (s->ctx.export_flags & V9FS_PATHNAME_FSCONTEXT) {
         qemu_co_rwlock_rdlock(&s->rename_lock);
     }
 }
 
 static inline void v9fs_path_unlock(V9fsState *s)
 {
-    if (s->ctx.flags & PATHNAME_FSCONTEXT) {
+    if (s->ctx.export_flags & V9FS_PATHNAME_FSCONTEXT) {
         qemu_co_rwlock_unlock(&s->rename_lock);
     }
 }