target/arm: add 64-bit S-EL2 to EL exception table

target/arm: add 64-bit S-EL2 to EL exception table

With the ARMv8.4-SEL2 extension, EL2 is a legal exception level in
secure mode, though it can only be AArch64.

This patch adds the target EL for exceptions from 64-bit S-EL2.

It also fixes the target EL to EL2 when HCR.{A,F,I}MO are set in secure
mode. Those values were never used in practice as the effective value of
HCR was always 0 in secure mode.

Signed-off-by: Rémi Denis-Courmont <remi.denis.courmont@huawei.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210112104511.36576-7-remi.denis.courmont@huawei.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>