[POWERPC] start-cpu has no return code

According to this document:

PowerPC Processor binding to: IEEE 1275-1994
Standard for Boot (Initialization, Configuration) Firmware
Revision: 2.1 (Approved Version)
Date: November 6, 1996

The start-cpu client interface has the following signature:

start-cpu
IN: nodeid, pc, arg
OUT: none

This patch reflects that, and makes us stop seeing a bogus OF_FAILURE if
we do actually check the return code of of_start_cpu. Tested on JS20
and JS21 blades.

Signed-off-by: Amos Waterland <apw@us.ibm.com>
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>

     1.1 --- a/xen/arch/powerpc/boot_of.c	Wed Aug 09 18:53:00 2006 -0400
     1.2 +++ b/xen/arch/powerpc/boot_of.c	Fri Aug 11 13:30:48 2006 -0400
     1.3 @@ -304,12 +304,11 @@ static int __init of_instance_to_path(in
     1.4  
     1.5  static int __init of_start_cpu(int cpu, u32 pc, u32 reg)
     1.6  {
     1.7 -    int rets[1] = { OF_FAILURE };
     1.8 +    int ret;
     1.9  
    1.10 -    if ( of_call("start-cpu", 3, 0, rets, cpu, pc, reg) == OF_FAILURE )
    1.11 -        return OF_FAILURE;
    1.12 +    ret = of_call("start-cpu", 3, 0, NULL, cpu, pc, reg);
    1.13  
    1.14 -    return rets[0];
    1.15 +    return ret;
    1.16  }
    1.17  
    1.18  static void __init of_test(const char *of_method_name)