mpc8[56]xx: Put localbus clock in sysinfo and gd

Currently MPC85xx and MPC86xx boards just calculate the localbus frequency
and print it out, but don't save it.

This changes where its calculated and stored to be more consistent with the
CPU, CCB, TB, and DDR frequencies and the MPC83xx localbus clock.

The localbus frequency is added to sysinfo and calculated when sysinfo is
set up, in cpu/mpc8[56]xx/speed.c, the same as the other frequencies are.

get_clocks() copies the frequency into the global data, as the other
frequencies are, into a new field that is only enabled for MPC85xx and
MPC86xx.

checkcpu() in cpu/mpc8[56]xx/cpu.c will print out the local bus frequency
from sysinfo, like the other frequencies, instead of calculating it on the
spot.

Signed-off-by: Trent Piepho <tpiepho@freescale.com>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Jon Loeliger <jdl@freescale.com>