Init Command buffer on inlineUploads in Vulkan

Init Command buffer on inlineUploads in Vulkan

When the first thing we do in a GrGpuCommandBuffer is do an inlineUpload,
we need to make sure we've initialized the command buffer in Vulkan.

BUG=skia:

Change-Id: Iabee770864a61697c55fb1df18b31862d8df3cdc
Reviewed-on: https://skia-review.googlesource.com/9970
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>