[POWERPC] Efika: Really, don't pretend to be CHRP

Fedora 9 works on Efika without the separate 'device-tree supplement',
thanks to the kernel's own fixups. With one exception -- because 'CHRP'
still appears on the 'machine:' line in /proc/cpuinfo, the installer
misdetects the platform and misconfigures yaboot, putting it into a PReP
boot partition instead of in the /boot filesystem where the Efika's
firmware could find it.

The kernel's fixups for Efika already correct one instance of 'chrp', in
the 'device_type' property. This fixes it in the 'CODEGEN,description'
property too, since that's what's exposed to userspace in /proc/cpuinfo.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Paul Mackerras <paulus@samba.org>