This patch adds the following support to the BL3-1 stage:
1. BL3-1 allows runtime services to specify and determine the security
state of the next image after BL3-1. This has been done by adding
the `bl31_set_next_image_type()` & `bl31_get_next_image_type()`
apis. The default security state is non-secure. The platform api
`bl31_get_next_image_info()` has been modified to let the platform
decide which is the next image in the desired security state.
2. BL3-1 exports the `bl31_prepare_next_image_entry()` function to
program entry into the target security state. It uses the apis
introduced in 1. to do so.
3. BL3-1 reads the information populated by BL2 about the BL3-2 image
into its internal data structures.
4. BL3-1 introduces a weakly defined reference `bl32_init()` to allow
initialisation of a BL3-2 image. A runtime service like the Secure
payload dispatcher will define this function if present.
Change-Id: Icc46dcdb9e475ce6575dd3f9a5dc7a48a83d21d1
35ca35119d