vkEnumerateLayers: Update to match upstream

The upstream vulkan.h header removed maxLayerCount parameter
from vkEnumerateLayers. This patch implements that change
for the sample driver and layers.
diff --git a/include/vulkan.h b/include/vulkan.h
index b46fdc4..28f1509 100644
--- a/include/vulkan.h
+++ b/include/vulkan.h
@@ -2133,7 +2133,7 @@
 typedef VkResult (VKAPI *PFN_vkDestroyDevice)(VkDevice device);
 typedef VkResult (VKAPI *PFN_vkGetGlobalExtensionInfo)(VkExtensionInfoType infoType, uint32_t extensionIndex, size_t* pDataSize, void* pData);
 typedef VkResult (VKAPI *PFN_vkGetPhysicalDeviceExtensionInfo)(VkPhysicalDevice gpu, VkExtensionInfoType infoType, uint32_t extensionIndex, size_t* pDataSize, void* pData);
-typedef VkResult (VKAPI *PFN_vkEnumerateLayers)(VkPhysicalDevice physicalDevice, size_t maxLayerCount, size_t maxStringSize, size_t* pOutLayerCount, char* const* pOutLayers, void* pReserved);
+typedef VkResult (VKAPI *PFN_vkEnumerateLayers)(VkPhysicalDevice physicalDevice, size_t maxStringSize, size_t* pLayerCount, char* const* pOutLayers, void* pReserved);
 typedef VkResult (VKAPI *PFN_vkGetDeviceQueue)(VkDevice device, uint32_t queueNodeIndex, uint32_t queueIndex, VkQueue* pQueue);
 typedef VkResult (VKAPI *PFN_vkQueueSubmit)(VkQueue queue, uint32_t cmdBufferCount, const VkCmdBuffer* pCmdBuffers, VkFence fence);
 typedef VkResult (VKAPI *PFN_vkQueueAddMemReferences)(VkQueue queue, uint32_t count, const VkDeviceMemory* pMems);
@@ -2296,7 +2296,6 @@
 
 VkResult VKAPI vkEnumerateLayers(
     VkPhysicalDevice                            physicalDevice,
-    size_t                                      maxLayerCount,
     size_t                                      maxStringSize,
     size_t*                                     pLayerCount,
     char* const*                                pOutLayers,