anv/blorp: Fix a crash in CmdClearColorImage

anv/blorp: Fix a crash in CmdClearColorImage

We should use anv_get_layerCount() to access layerCount of VkImageSub-
resourceRange in anv_CmdClearColorImage and anv_CmdClearDepthStencil-
Image, which handles the VK_REMAINING_ARRAY_LAYERS (~0) case.

Test: Sample multithreadcmdbuf from LunarG can run without crash

Signed-off-by: Xu Randy <randy.xu@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: "13.0 17.0" <mesa-stable@lists.freedesktop.org>