intel/error2aub: build a list of BOs before writing them

intel/error2aub: build a list of BOs before writing them

The error state contains several kind of BOs, including the context
image which we will want to write in a later commit. Because it can
come later in the error state than the user buffers and because we
need to write it first in the aub file, we have to first build a list
of BOs and then write them in the appropriate order.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>