mpc83xx: boot time regression, move LCRR setup back to cpu_init_f

Commit c7190f02 (retain POR values of non-configured ACR, SPCR, SCCR,
and LCRR bitfields) moved the LCRR assignment to after relocation
to RAM because of the potential problem with changing the local bus
clock while executing from flash.

This change unfortunately adversely affects the boot time, as running
all code up to cpu_init_r can cause significant slowdown.

E.G. on a 8347 board a bootup time increase of ~600ms has been observed:

   0.020 CPU:   e300c1, MPC8347_PBGA_EA, Rev: 3.0 at 400 MHz, CSB: 266.667 MHz
   0.168 RS:    232
   0.172 I2C:   ready
   0.176 DRAM:  64 MB
   1.236 FLASH: 32 MB

Versus:

   0.016 CPU:   e300c1, MPC8347_PBGA_EA, Rev: 3.0 at 400 MHz, CSB: 266.667 MHz
   0.092 RS:    232
   0.092 I2C:   ready
   0.096 DRAM:  64 MB
   0.644 FLASH: 32 MB

So far no boards have needed the late LCRR setup, so simply revert it
for now - If it is needed at a later time, those boards can either do
their own final LCRR setup in board code (E.G. in board_early_init_r),
or we can introduce a CONFIG_SYS_LCRR_LATE config option to only do
the setup in cpu_init_r.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>