tee: optee: enable dynamic SHM support

Previous patches added various features that are needed for dynamic SHM.
Dynamic SHM allows Normal World to share any buffers with OP-TEE.
While original design suggested to use pre-allocated region (usually of
1M to 2M of size), this new approach allows to use all non-secure RAM for
command buffers, RPC allocations and TA parameters.

This patch checks capability OPTEE_SMC_SEC_CAP_DYNAMIC_SHM. If it was set
by OP-TEE, then kernel part of OP-TEE will use kernel page allocator
to allocate command buffers. Also it will set TEE_GEN_CAP_REG_MEM
capability to tell userspace that it supports shared memory registration.

Signed-off-by: Volodymyr Babchuk <vlad.babchuk@gmail.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>