sys-boot/tboot: Fix breakage triggered by mount-boot update.

sys-boot/tboot: Fix breakage triggered by mount-boot update.

mount-boot_mount_boot_partition() was an internal and undocumented
function which shouldn't have been called, in the first place.

Delete it from pkg_postinst without replacement, because the relevant
checks in mount-boot_check_status will have been called already in
mount-boot_pkg_preinst.

Drop the call to mount-boot_pkg_postinst as well, because that
function is a no-op now.

Package-Manager: Portage-2.3.81, Repoman-2.3.20
Signed-off-by: Ulrich Müller <ulm@gentoo.org>