drm/amdgpu: refine ras codes for GC utc of aldebaran

The bank number of both VML2 and ATCL2 are changed to 8, so refine
related codes to avoid defining long name arrays.

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