VMware.Hv.Helper does not set the VGPUGridProfile variable from Json

[lindenjonas]

In the Json spec when creating a Desktop Pool, there is a property called DesktopSettings.displayProtocolSettings.pcoipDistplaySettings.VGPUGridProfile . The $VGPUGridProfile variable is NOT being set from the Json object. This causes the New-HVPool function to fail when you want vGPU support. The code should be equivalent to the code for the enableGRIDvGPUs property.