drm/xe/stolen: ignore first page for FBC

We have observed underruns on some platforms if the CFB offset is within
the first page of stolen. Just like i915 skip the first page.

v2 (Maarten)
  - Also align the start.

BSpec: 50214
Reported-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240412150301.273344-4-matthew.auld@intel.com

drivers/gpu/drm/xe/compat-i915-headers/i915_gem_stolen.h

@@ -19,8 +19,13 @@ static inline int i915_gem_stolen_insert_node_in_range(struct xe_device *xe,
 	int err;
 	u32 flags = XE_BO_FLAG_PINNED | XE_BO_FLAG_STOLEN;
 
-	if (align)
+	if (start < SZ_4K)
+		start = SZ_4K;
+
+	if (align) {
 		size = ALIGN(size, align);
+		start = ALIGN(start, align);
+	}
 
 	bo = xe_bo_create_locked_range(xe, xe_device_get_root_tile(xe),
 				       NULL, size, start, end,