drm/amdkfd: Move the ignore_crat check before the CRAT table get

If the ignore_crat is set to non-zero value, it's no point getting
the CRAT table, so just move the ignore_crat check before we get the
CRAT table.

Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>