Moved PowerPC cache management code to libcpu. Also compiled

mpc8xx libcpu support for the first time and remove includes
of bsp.h, references to BSP_Configuration, and Cpu_table.  All
of these can be obtained directly from RTEMS now.

c/src/lib/libcpu/powerpc/mpc8xx/timer/timer.c

@@ -43,12 +43,9 @@
  *  $Id$
  */
 
-#include <bsp.h>
 #include <rtems.h>
 #include <mpc8xx.h>
 
-extern rtems_cpu_table           Cpu_table;             /* owned by BSP */
-
 static volatile rtems_unsigned32 Timer_starting;
 static rtems_boolean Timer_driver_Find_average_overhead;
 
@@ -86,10 +83,10 @@ int Read_timer(void)
     return total;          /* in XXX microsecond units */
 
   else {
-    if ( total < Cpu_table.timer_least_valid ) {
+    if ( total < rtems_cpu_configuration_get_timer_least_valid() ) {
       return 0;            /* below timer resolution */
     }
-    return (total - Cpu_table.timer_average_overhead);
+    return (total - rtems_cpu_configuration_get_timer_average_overhead());
   }
 }