drm/amdgpu: fix the gb_addr_config_fields init value mismatch

For gfx_v9_4_3 specifically, before regGB_ADDR_CONFIG is overwritten
in gfx hw_init it is read out to popluate the gb_addr_config_fields
in the sw_init stage, which causes mismatch.

Fix it by using the golden value in sw_init as well.

v2: This is a driver-set golden reg and keep as it is (Lijo)

Signed-off-by: Shiwu Zhang <shiwu.zhang@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>