drm/amdgpu/psp: add structure to support load toc in psp (v2)

Update the psp interface for the new commands.

v2: rebase (Alex)

FIXME:
GFX_CMD_ID_PROG_REG     = 0x0000000B,   /* program regs */
GFX_CMD_ID_LOAD_TOC     = 0x0000000B,   /* Load TOC and obtain TMR size */

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