drm/amdgpu: add the support of XGMI link for GC 9.4.3

Add the xgmi LFB_CNTL/LBF_SIZE reg addresses to fetch the xgmi info from.

v2: move get_xgmi_info() to GC_V9_4_3 sepecific source files to utilize
the register definitions specific for GC_V9_4_3
v3: remove the duplicated register definitions
v4: enable xgmi based on asic_type as XGMI_IP ver is not available
yet for IP discovery

Signed-off-by: Shiwu Zhang <shiwu.zhang@amd.com>
Reviewed-by: Le Ma <Le.Ma@amd.com>
Ack-by: Lijo Lazar <Lijo.Lazar@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>