SPM: Set STATIC_HANDLE_IDX_BIT_WIDTH as 5

The current used number of stateless handle is 32, which occupies only
5 bits. So change STATIC_HANDLE_IDX_BIT_WIDTH from 8 to 5 to avoid
unnecessary static handle index validation because it can not be larger
than 32.

Related document is also updated in this patch.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I5bb9119ff7c03cc6a067fb291e3cbff2627ba49d
4 files changed