target/arm: Implement FEAT_SCTLR2 and enable with -cpu max

target/arm: Implement FEAT_SCTLR2 and enable with -cpu max

Add FEAT_SCTLR2, which introduces the SCTLR2_EL1, SCTLR2_EL2, and
SCTLR2_EL3 registers. These registers are extensions of the SCTLR_ELx
ones.

Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20250727074202.83141-4-richard.henderson@linaro.org
Message-ID: <20250711140828.1714666-4-gustavo.romero@linaro.org>
[rth: Remove FEAT_MEC code; handle SCR and HCRX enable bits.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>