Add tpm_extendpcr utility to the tpm-tools recipe.

This needs to go upstream.
Add coreutils to the initramfs to get 'sha1sum' needed to measure rootfs.img before switch_root.

This adds ~3MB to the initramfs image.  Would be nice if we could pull
in just the single binary instead of the whole coreutils package.
Add the core-image-tpm image as the rootfs for the measured-image-bootimg live image.  Add kernel parmateters for the image and the PCR to store it's hash in.

Currently using PCR[9] which is part of the SRTM.  Some research
needs to be done to determine which PCR is the appropriate place to
store this measurement.  Currently locality limits us to PCRs for the
SRTM or PCRs > 22 for reasons of locality.
First usable version of init-boot-tpm.sh that will measure and switch_root to the live rootfs.img