io_uring/rsrc: skip NULL file/buffer checks in io_free_rsrc_node()

io_uring/rsrc: skip NULL file/buffer checks in io_free_rsrc_node()

io_rsrc_node's of type IORING_RSRC_FILE always have a file attached
immediately after they are allocated. IORING_RSRC_BUFFER nodes won't be
returned from io_sqe_buffer_register()/io_buffer_register_bvec() until
they have a io_mapped_ubuf attached.

So remove the checks for a NULL file/buffer in io_free_rsrc_node().

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Link: https://lore.kernel.org/r/20250228235916.670437-5-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>