drm/i915/gvt: Do not copy the uninitialized pointer from fb_info

In the code the memcpy() function copied uninitialized pointer in fb_info
to dmabuf_obj->info. Later the pointer in dmabuf_obj->info will be
initialized. To make the code aligned with requirements of the klocwork
static code analyzer, the uninitialized pointer should be initialized
before memcpy().

v2:
- Initialize fb_info.obj in vgpu_get_plane_info(). (Colin Xu)

This patch fixed the critical issue #632 reported by klockwork.

Signed-off-by: Aleksei Gimbitskii <aleksei.gimbitskii@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Colin Xu <colin.xu@intel.com>
Reviewed-by: Colin Xu <colin.xu@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>