drm/amd/display: Load NV12 SOC BB from firmware

[Why]

Previous SOC bounding box firmware loading logic was for NV10, when we
still had it in firmware. Now that it's brought into driver code, and
NV12 BB is in firmware, this logic needs to be repurposed for NV12.

[How]

Set SOC_BOUNDING_BOX_VALID to false, and add the dcn_2_0_nv12_soc BB
struct. In init_soc_bounding_box, load firmware to nv12 BB instead.

In addition, conditionally update and patch the BB, depending on ASIC
REV.
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Hersen Wu <hersenxs.wu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>