13.10: remove bootwrapper instructions

We no longer support booting with the bootwrapper, users should use UEFI
instead.

Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>
13.10: touch uefi-vars.fd

Some versions of the models crash if the uefi-vars.fd file doesn't
exist, so make sure it exists before running the model.

Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>