powerpc/fsl_booke: Add support to boot from core other than 0

First we check to see if we are the first core booting up. This
is accomplished by comparing the boot_cpuid with -1, if it is we
assume this is the first core coming up.

Secondly, we need to update the initial thread info structure
to reflect the actual cpu we are running on otherwise
smp_processor_id() and related functions will return the default
initialization value of the struct or 0.

Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>