[graphite] Disable SSBOs for Dawn/Vulkan

Graphite/Dawn/Vulkan is hitting dawn device loss due to out-of-bounds
memory access in a shader on Android. The root cause hasn't been worked
out yet so disabled SSBOs with the Vulkan backend for the time being.
This unblocks starting a finch experiment on Android.

Bug: chromium:344963958
Change-Id: I7eb9e0bdd649c2c89ed9b9c3227e9ffda47f388c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/896480
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Nicolette Prevost <nicolettep@google.com>
1 file changed