Microsoft are using Intel/Altera FPGAs in the datacenter, and not likely for mass produced devices like this.
While it is possible they are using FPGAs for the Hololens Processing Unit, I seriously doubt it. The FPGA needed to exceed the performance of a high-end mobile GPU (OpenCL/CUDA for Deep Learning/AI) would have an excessive power consumption for a mobile device.
Another factor is that higher end FPGAs are expensive ($200+ wholesale) and typically cost thousands each, and not suited to a mass produced consumer device.
As for who made this HPU, I'd say AMD helped design it and GlobalFoundries (or maybe TSMC) are doing the production.
While it is possible they are using FPGAs for the Hololens Processing Unit, I seriously doubt it. The FPGA needed to exceed the performance of a high-end mobile GPU (OpenCL/CUDA for Deep Learning/AI) would have an excessive power consumption for a mobile device.
Another factor is that higher end FPGAs are expensive ($200+ wholesale) and typically cost thousands each, and not suited to a mass produced consumer device.
As for who made this HPU, I'd say AMD helped design it and GlobalFoundries (or maybe TSMC) are doing the production.