drm/i915/gvt: Deliver guest cursor hotspot info

Guest OS driver uses PV info registers to deliver cursor hotspot info
to host. This patch is used to get cursor hotspot info from virtual
registers and deliver it to host userspace.

v4->v5:
- remove CI warning.

v3->v4:
- return UINT_MAX when x_hot/y_hot is invalid. (Zhenyu)
- correct version.

v2->v3:
- add validate_hotspot(). (Zhenyu)

v1->v2:
- name as cursor_x_hot/cursor_y_hot. (Zhenyu)
- use i915_reg_t definition instead of magic numbers. (Zhenyu)

Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/i915_pvinfo.h

@@ -93,7 +93,10 @@ struct vgt_if {
 	u32 rsv5[4];
 
 	u32 g2v_notify;
-	u32 rsv6[7];
+	u32 rsv6[5];
+
+	u32 cursor_x_hot;
+	u32 cursor_y_hot;
 
 	struct {
 		u32 lo;