gvt_pin_guest_page extracted some of the gvt_dma_map_page functionality:
commit 79e542f5af79 ("drm/i915/kvmgt: Support setting dma map for huge pages")
And yet, part of it was reintroduced in:
commit 39b4cbadb9a9 ("drm/i915/kvmgt: Check the pfn got from vfio_pin_pages")
Causing kvmgt part to no longer build. Let's remove it.