drm/i915: Hide enable_gvt modparam when not compiled in

Hide the enable_gvt modparam in the default scenario where
support has not been compiled in.

Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181116144447.7836-1-joonas.lahtinen@linux.intel.com

drivers/gpu/drm/i915/i915_params.c

@@ -167,8 +167,10 @@ i915_param_named_unsafe(inject_load_failure, uint, 0400,
 i915_param_named(enable_dpcd_backlight, bool, 0600,
 	"Enable support for DPCD backlight control (default:false)");
 
+#if IS_ENABLED(CONFIG_DRM_I915_GVT)
 i915_param_named(enable_gvt, bool, 0400,
 	"Enable support for Intel GVT-g graphics virtualization host support(default:false)");
+#endif
 
 static __always_inline void _print_param(struct drm_printer *p,
 					 const char *name,