85xx: Add support for not releasing secondary cores via 'mp_holdoff'

Some OSes require that secondary cores not be initialized when they
are booted (eg VxWorks).  By default when U-Boot is compiled with the
CONFIG_MP option all secondary cores are brought out of reset and held
in spinloops.  Setting the "mp_holdoff" environment variable to 'yes'
or '1' will cause U-Boot to leave secondary cores in their default
state.

Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/cpu/mpc85xx/mp.h b/arch/powerpc/cpu/mpc85xx/mp.h
index 3422cc1..87bac37 100644
--- a/arch/powerpc/cpu/mpc85xx/mp.h
+++ b/arch/powerpc/cpu/mpc85xx/mp.h
@@ -6,6 +6,7 @@
 ulong get_spin_phys_addr(void);
 ulong get_spin_virt_addr(void);
 u32 get_my_id(void);
+int hold_cores_in_reset(int verbose);
 
 #define BOOT_ENTRY_ADDR_UPPER	0
 #define BOOT_ENTRY_ADDR_LOWER	1