raw/ifpga: introduce AFU driver framework

raw/ifpga: introduce AFU driver framework

AFU (Acceleration Function Unit) is part of FPGA and enumerated
by ifpga driver.
This driver implements common AFU device interfaces and exposes
them to application as standard raw device APIs.
Normally application can operate specified AFU as below,
1. call rte_rawdev_pmd_get_named_dev() to find AFU device.
2. call rte_rawdev_configure() to initialize AFU device.
3. call rte_rawdev_selftest() to test AFU device.

Signed-off-by: Wei Huang <wei.huang@intel.com>
Acked-by: Tianfei Zhang <tianfei.zhang@intel.com>
Reviewed-by: Rosen Xu <rosen.xu@intel.com>