hw/i386/pc: Confine system flash handling to pc_sysfw

Rather than distributing PC system flash handling across three files, let's
confine it to one. Now, pc_system_firmware_init() creates, configures and cleans
up the system flash which makes the code easier to understand. It also avoids
the extra call to pc_system_flash_cleanup_unused() in the Xen case.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240208220349.4948-7-shentey@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
4 files changed