drm/amdkfd: Eliminate ops_asic_specific in kernel queue

The ops_asic_specific function pointers are actually quite generic after
using a simple if condition. Eliminate it by code refactoring.

Signed-off-by: Yong Zhao <Yong.Zhao@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>