target/arm: Only set CPU_INTERRUPT_EXITTB for TCG

Commit 34c45d53026 ("target-arm: kvm - re-inject guest debug exceptions") removed CPU_INTERRUPT_EXITTB from KVM, but it also appears on HVF. Better to restrict it to TCG. Suggested-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org> Reviewed-by: Pierrick Bouvier <pierrick.bouvier@oss.qualcomm.com> Message-Id: <20250630130937.3487-2-philmd@linaro.org> Signed-off-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>