mount/fuse: do not forget the root inode

In batch forgetting of inodes, nodeid should be checked and if it is for
root, then it should not be sent forget.

Change-Id: I99bd91ba70d8be4df88ddac005e38c449f4ed7d9
BUG: 990744
Signed-off-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-on: http://review.gluster.org/5471
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Reviewed-by: Anand Avati <avati@redhat.com>