api: update: pass correct config when creating disks

api: update: pass correct config when creating disks

While the new options should be written to the pending config, the
decisions (currently only one) in create_disks needs to be made for
the current config.

Seems to fix EFI disk creation, but actually, it's only
future-proofing, because, currently, the same OVMF_VARS file is
used independently of $smm.

The correct config is also needed to determine the correct size for
the EFI disk for the upcoming import-from feature.

Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>