target/arm: Extend arm_fi_to_lfsc to level -1

target/arm: Extend arm_fi_to_lfsc to level -1

With FEAT_LPA2, rather than introducing translation level 4,
we introduce level -1, below the current level 0.  Extend
arm_fi_to_lfsc to handle these faults.

Assert that this new translation level does not leak into
fault types for which it is not defined, which allows some
masking of fi->level to be removed.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220301215958.157011-12-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>