drm/i915/kvmgt: Fix compilation error

drm/i915/kvmgt: Fix compilation error

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.

Reported-by: Tomasz Lis <tomasz.lis@intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Cc: Changbin Du <changbin.du@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180712155330.32055-1-michal.winiarski@intel.com