firmware: google: Init coreboot bus with subsys_initcall()

firmware: google: Init coreboot bus with subsys_initcall()

Using module_init()/device_initcall() is too late to initialize
the coreboot bus, as there might already be drivers that depend
on it.

So far this hasn't been a problem, as coreboot controls all device
creation. Initializing the coreboot bus earlier in subsys_initcall()
will allow for external coreboot drivers to register themselves
with device_initcall(). Prepares coreboot to support additional
coreboot drivers from other subsystems.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Tzung-Bi Shih <tzungbi@kernel.org>
Acked-by: Julius Werner <jwerner@chromium.org>
Link: https://patch.msgid.link/20260217155836.96267-7-tzimmermann@suse.de