drm/i915/gvt: Disable compression workaround for Gen9

With enabling this workaround, can observe GPU hang issue on Gen9. As
currently host side doesn't have this workaround, disable it from GVT
side.

v2:
- Fix indent error.(Zhenyu)

Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>