sparc32: always define boot_cpu_id

Define boot_cpu_id in single-processor kernels as well. This is
to support architectures which can boot on other than CPU0.

Sam Ravnborg has written the cleanup parts by extracting
boot_cpu_id from smp_32.c into setup_32.c and cleaned up
sun4d_irq.c.

boot_cpu_id was initialized before BSS was cleared in
sun4c_continue_boot, instead boot_cpu_id is set to 0xff to
avoid BSS. If boot_cpu_id is untouched (0xff) by bootup code
it will be overwritten to 0. boot_cpu_id4 is automatically
calculated in common code.

Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/include/asm/setup.h b/arch/sparc/include/asm/setup.h
index 2643c62..64718ba 100644
--- a/arch/sparc/include/asm/setup.h
+++ b/arch/sparc/include/asm/setup.h
@@ -11,4 +11,16 @@
 # define COMMAND_LINE_SIZE 256
 #endif
 
+#ifdef __KERNEL__
+
+#ifdef CONFIG_SPARC32
+/* The CPU that was used for booting
+ * Only sun4d + leon may have boot_cpu_id != 0
+ */
+extern unsigned char boot_cpu_id;
+extern unsigned char boot_cpu_id4;
+#endif
+
+#endif /* __KERNEL__ */
+
 #endif /* _SPARC_SETUP_H */