platform/x86: simatic-ipc: correct name of a model

What we called IPC427G should be renamed to BX-39A to be more in line
with the actual product name.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Link: https://lore.kernel.org/r/20221222103720.8546-2-henning.schild@siemens.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>