drm/amdgpu/psp: move PSP memory alloc from hw_init to sw_init

Memory allocations should be done in sw_init.  hw_init should
just be hardware programming needed to initialize the IP block.
This is how most other IP blocks work.  Move the GPU memory
allocations from psp hw_init to psp sw_init and move the memory
free to sw_fini.  This also fixes a potential GPU memory leak
if psp hw_init fails.

Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>