drm/i915/gvt: Fix klocwork issues about data size

Add llu suffix and cast operator to fix the klocwork warning about
"Operands in a bitwise operation have different size"

Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200324123021.15831-1-tina.zhang@intel.com