Currently the only tag-setting instructions always do so in the
context of the current EL, and so we only need one ATA bit in the TB
flags.  The FEAT_MOPS SETG instructions include ones which set tags
for a non-privileged access, so we now also need the equivalent "are
tags enabled?" information for EL0.

Add the new TB flag, and convert the existing 'bool ata' field in
DisasContext to a 'bool ata[2]' that can be indexed by the is_unpriv
bit in an instruction, similarly to mte[2].

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230912140434.1333369-9-peter.maydell@linaro.org