Mark dca_init as a subsys_initcall since it needs to be ready to go
before dependent drivers start registering themselves.

Cc: <stable@kernel.org>
Reported-and-tested-by: Mark Rustad <mark_rustad@Xiotech.com>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>