On the x13s, using the EfiLoaderData memory type for the memory block

On the x13s, using the EfiLoaderData memory type for the memory block
that we load the kernel into doesn't work.  But changing it to EfiLoaderCode
makes it work.  Presumably the firmware creates a mapping with executable
permissions in that case, which is obviously needed for executing kernel
code.

ok patrick@, mlarkin@