target/m68k: Restrict semihosting to TCG

target/m68k: Restrict semihosting to TCG

The semihosting feature depends on TCG (due to the probe_access
API access). Although TCG is the single accelerator currently
available for the m68k target, use the Kconfig "imply" directive
which is more correct (if we were to support a different accel).

Reported-by: Anton Johansson <anjo@rev.ng>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20240717105723.58965-5-philmd@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240718094523.1198645-12-alex.bennee@linaro.org>