drm/i915: enable vGPU detection for all

vGPU capability is handled by GVT-g host driver, not needed to
put extra HW check for vGPU detection. And we'll actually support
vGPU from BDW.

Signed-off-by: Ping Gao <ping.a.gao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: drm-intel-fixes@lists.freedesktop.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160906040412.1274-2-zhenyuw@linux.intel.com