powerpc: Initialize secondary CPU setup for 32-bit SMP

32-bit SMP powermacs weren't booting with ARCH=powerpc because the
boot cpu wasn't saving away the state of various control registers,
but the secondary CPUs were loading them from the uninitialized
state.  This adds the necessary save-state call.
Signed-off-by: NPaul Mackerras <paulus@samba.org>

arch/powerpc/kernel/head_32.S

@@ -1100,6 +1100,7 @@ start_here:
 	mr	r3,r31
 	mr	r4,r30
 	bl	machine_init
+	bl	__save_cpu_setup
 	bl	MMU_init
 
 #ifdef CONFIG_APUS