fusefs: fix some resource leaks

fusefs would leak tickets in three cases:

• After FUSE_CREATE, if the server returned a bad inode number.
• After a FUSE_FALLOCATE operation during VOP_ALLOCATE
• After a FUSE_FALLOCATE operation during VOP_DEALLOCATE

Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D38526

(cherry picked from commit 1bdf879b97b686a8f36fdba050b68f9e7493f363)

MFC Note: changes to VOP_DEALLOCATE are not MFCed, because that VOP does
not exist in stable/13.