vpc: Split off vpc_ignore_current_size() helper

vpc: Split off vpc_ignore_current_size() helper

In preparation to making changes to the logic deciding whether CHS or
'current_size' need to be used in determining the image size, split off
vpc_ignore_current_size() helper.

No functional change intended.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-ID: <20241212134504.1983757-2-vkuznets@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>