layers: Move ValidateMapImageLayouts out of CV

Change-Id: Ib9d9c169b1306a7ed6f243bbb957719305340a2e
diff --git a/layers/buffer_validation.h b/layers/buffer_validation.h
index 5375722..4ade0e6 100644
--- a/layers/buffer_validation.h
+++ b/layers/buffer_validation.h
@@ -150,4 +150,7 @@
 
 bool ValidateLayouts(core_validation::layer_data *dev_data, VkDevice device, const VkRenderPassCreateInfo *pCreateInfo);
 
+bool ValidateMapImageLayouts(core_validation::layer_data *dev_data, VkDevice device, DEVICE_MEM_INFO const *mem_info,
+                             VkDeviceSize offset, VkDeviceSize end_offset);
+
 #endif  // CORE_VALIDATION_BUFFER_VALIDATION_H_