system: propagate Error to gdbserver_start (and other device setups)

system: propagate Error to gdbserver_start (and other device setups)

This started as a clean-up to properly pass a Error handler to the
gdbserver_start so we could do the right thing for command line and
HMP invocations.

Now that we have cleaned up foreach_device_config_or_exit() in earlier
patches we can further simplify by it by passing &error_fatal instead
of checking the return value. Having a return value is still useful
for HMP though so tweak the return to use a simple bool instead.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20250116160306.1709518-11-alex.bennee@linaro.org>