drm/amdgpu: New interface to get IP discovery binary v3

drm/amdgpu: New interface to get IP discovery binary v3

Implement a driver path to read the IP discovery
binary offset and size from DRIVER_SCRATCH registers
BIOS signals usage by setting a feature flag that
instructs the driver to use this method. Otherwise,
fallback to legacy approach.

v2: Simplify discovery offset/size retrieval in
get_tmr_info

v3: Update get_tmr_info to cover discovery offset
and size retrieval for both bare-metal and sriov

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