[SPARC64]: Fix sparse warnings wrt. machine_alt_power_off().

arch/sparc64/kernel/process.c:123:6: warning: symbol 'machine_alt_power_off' was not declared. Should it be static?
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc64/kernel/power.c

@@ -20,6 +20,7 @@
 #include <asm/of_device.h>
 #include <asm/io.h>
 #include <asm/sstate.h>
+#include <asm/reboot.h>
 
 #include <linux/unistd.h>
 
@@ -39,8 +40,6 @@ static irqreturn_t power_handler(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-extern void machine_halt(void);
-extern void machine_alt_power_off(void);
 static void (*poweroff_method)(void) = machine_alt_power_off;
 
 void machine_power_off(void)

arch/sparc64/kernel/process.c

@@ -47,6 +47,7 @@
 #include <asm/unistd.h>
 #include <asm/hypervisor.h>
 #include <asm/sstate.h>
+#include <asm/reboot.h>
 
 /* #define VERBOSE_SHOWREGS */
 

include/asm-sparc64/reboot.h

+#ifndef _SPARC64_REBOOT_H
+#define _SPARC64_REBOOT_H
+
+extern void machine_alt_power_off(void);
+
+#endif /* _SPARC64_REBOOT_H */