Fix stall in Vk clear

TBR=egdaniel@google.com
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1765863003

Review URL: https://codereview.chromium.org/1765863003

src/gpu/vk/GrVkGpu.cpp

@@ -1041,6 +1041,8 @@ void GrVkGpu::onClear(GrRenderTarget* target, const SkIRect& rect, GrColor color
         }
         clearRect.rect.offset = { vkRect.fLeft, vkRect.fTop };
         clearRect.rect.extent = { (uint32_t)vkRect.width(), (uint32_t)vkRect.height() };
+        clearRect.baseArrayLayer = 0;
+        clearRect.layerCount = 1;
 
         const GrVkRenderPass* renderPass = vkRT->simpleRenderPass();
         SkASSERT(renderPass);