tee: optee: Fix dynamic shm pool allocations

In case of dynamic shared memory pool, kernel memory allocated using
dmabuf_mgr pool needs to be registered with OP-TEE prior to its usage
during optee_open_session() or optee_invoke_func().

So fix dmabuf_mgr pool allocations via an additional call to
optee_shm_register().

Also, allow kernel pages to be registered as shared memory with OP-TEE.

Fixes: 9733b072

 ("optee: allow to work without static shared memory")
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>