[POWERPC] Remove obsolete PPC_52xx and update CLASSIC32 comment

The support for the 52xx-based systems is now included under
CONFIG_CLASSIC32, since the 52xx chips have a 603e-based core.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Paul Mackerras <paulus@samba.org>
1 file changed