Fix for PowerVR Rogue GE8320 random flickering polygons (#3539)

src/renderer_vk.cpp

@@ -5286,7 +5286,7 @@ retry:
 		BGFX_PROFILER_SCOPE("BufferVK::update", kColorFrame);
 		BX_UNUSED(_discard);
 
-		StagingBufferVK stagingBuffer = s_renderVK->allocFromScratchStagingBuffer(_size, 8, _data);
+		StagingBufferVK stagingBuffer = s_renderVK->allocFromScratchStagingBuffer(_size, 16, _data);
 
 		VkBufferCopy region;
 		region.srcOffset = stagingBuffer.m_offset;