drm/amdgpu: Unify PSP TA context

Remove all TA binary structures and add the specific binary
structure in struct ta_context.

Signed-off-by: Candice Li <candice.li@amd.com>
Reviewed-by: John Clements <john.clements@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>