powerpc/85xx: sbc8560 - Fix warm reboot with board specific reset function

The existing fsl_rstcr_restart function is not applicable to the
mpc8560. The Global Utilities Block on this earlier CPU doesn't have
the control/reset register at 0xe00b0.  This implements a board
specific reset function that uses the RCR(Reset Control Register) of
the sbc8560's EPLD to do a reset.

Signed-off-by: Liang Li <Liang.Li@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>