ioat: convert ioat_probe to pcim/devm

The driver currently duplicates much of what these routines offer, so
just use the common code.  For example ->irq_mode tracks what interrupt
mode was initialized, which duplicates the ->msix_enabled and
->msi_enabled handling in pcim_release.

This also adds a check to the return value of dma_async_device_register,
which can fail.

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>