configure: always define HAVE_LIBDRM_ATOMIC_PRIMITIVES and HAVE_LIB_ATOMIC_OPS

Fixes #if undefined warnings

Signed-off-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>