Register and enable interrupts after the edac registration. Otherwise
incomming ecc error interrupts lead to crashes during device setup.

Fixing this in drivers for mc and l2.
Signed-off-by: Robert Richter <robert.richter@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Cc: stable <stable@vger.kernel.org>     # 3.6+
Signed-off-by: Robert Richter <rric@kernel.org>