hw/smbios: Remove "smbios_ipmi.h"

hw/smbios: Remove "smbios_ipmi.h"

This header only declare a single function: smbios_build_type_38_table().
We already have a header that declares such functions: "smbios_build.h".
Move the declaration and remove the header.

Reviewed-by: Corey Minyard <cminyard@mvista.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>