drm/amdkfd: add helper to generate cache info from gfx config

Rather than using hardcoded tables, we can use the gfx and
gmc config pulled from the IP discovery table to generate the
cache configuration.

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>