powerpc/xive: Make debug routines static

This fixes a compile error with W=1.

CC      arch/powerpc/sysdev/xive/common.o
../arch/powerpc/sysdev/xive/common.c:1568:6: error: no previous prototype for ‘xive_debug_show_cpu’ [-Werror=missing-prototypes]
 void xive_debug_show_cpu(struct seq_file *m, int cpu)
      ^~~~~~~~~~~~~~~~~~~
../arch/powerpc/sysdev/xive/common.c:1602:6: error: no previous prototype for ‘xive_debug_show_irq’ [-Werror=missing-prototypes]
 void xive_debug_show_irq(struct seq_file *m, u32 hw_irq, struct irq_data *d)
      ^~~~~~~~~~~~~~~~~~~

Fixes: 930914b7 ("powerpc/xive: Add a debugfs file to dump internal XIVE state")
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914211007.2285999-5-clg@kaod.org

arch/powerpc/sysdev/xive/common.c

@@ -1565,7 +1565,7 @@ static int __init xive_off(char *arg)
 }
 __setup("xive=off", xive_off);
 
-void xive_debug_show_cpu(struct seq_file *m, int cpu)
+static void xive_debug_show_cpu(struct seq_file *m, int cpu)
 {
 	struct xive_cpu *xc = per_cpu(xive_cpu, cpu);
 
@@ -1599,7 +1599,7 @@ void xive_debug_show_cpu(struct seq_file *m, int cpu)
 	seq_puts(m, "\n");
 }
 
-void xive_debug_show_irq(struct seq_file *m, u32 hw_irq, struct irq_data *d)
+static void xive_debug_show_irq(struct seq_file *m, u32 hw_irq, struct irq_data *d)
 {
 	struct irq_chip *chip = irq_data_get_irq_chip(d);
 	int rc;