qapi: Rename TargetInfo structure as QemuTargetInfo

qapi: Rename TargetInfo structure as QemuTargetInfo

The QAPI-generated 'TargetInfo' structure name is only used
in a single file. We want to heavily use another structure
similarly named. Rename the QAPI one, since structure names
are not part of the public API.

Suggested-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20250422145502.70770-2-philmd@linaro.org>