Revert "drm/amdkfd: fix gfx_target_version for certain 11.0.3 devices"

This reverts commit 28ebbb49.

Revert this commit as apparently the LLVM code to take advantage of
this never landed.

Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Feifei Xu <feifei.xu@amd.com>