documentation: remove references to cpu_*_map.

This has been obsolescent for a while, fix documentation and
misc comments.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/arch/mips/sibyte/bcm1480/smp.c b/arch/mips/sibyte/bcm1480/smp.c
index 63d2211..de88e22 100644
--- a/arch/mips/sibyte/bcm1480/smp.c
+++ b/arch/mips/sibyte/bcm1480/smp.c
@@ -138,7 +138,7 @@
 
 /*
  * Use CFE to find out how many CPUs are available, setting up
- * cpu_possible_map and the logical/physical mappings.
+ * cpu_possible_mask and the logical/physical mappings.
  * XXXKW will the boot CPU ever not be physical 0?
  *
  * Common setup before any secondaries are started