anv: handle errors while allocating new binding table blocks

anv: handle errors while allocating new binding table blocks

Also, we had a couple of instances in flush_descriptor_sets() were
we were returning a VkResult directly upon error, but the return
value of this function is not a VkResult but a uint32_t dirty mask,
so simply return 0 in these cases which reduces the amount of
work the driver will do after the error has been raised.

Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>