raw/ioat: fix missing close function

raw/ioat: fix missing close function

When rte_rawdev_pmd_release() is called, rte_rawdev_close() looks for a
dev_close function for the device causing a segmentation fault when no
close() function is implemented for a driver.

This patch resolves the issue by adding a stub function ioat_dev_close().

Fixes: f687e842e328 ("raw/ioat: introduce IOAT driver")
Cc: stable@dpdk.org
Reported-by: Sunil Pai G <sunil.pai.g@intel.com>
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Reviewed-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Sunil Pai G <sunil.pai.g@intel.com>
Acked-by: Radu Nicolau <radu.nicolau@intel.com>