[PATCH] powerpc/irq: Fix build with CONFIG_PROC_FS=n

Commit fbb22ceaaf8f ("powerpc/irq: Make irqstats array based") made
arch_show_interrupts() call irq_proc_emit_counts(). That function lives
in kernel/irq/proc.c, which is only built with CONFIG_PROC_FS, so
kernels without procfs no longer link:

  powerpc64-linux-ld: arch/powerpc/kernel/irq.o: in function `arch_show_interrupts':
  arch/powerpc/kernel/irq.c:134:(.text+0x4b8c): undefined reference to `irq_proc_emit_counts'

arch_show_interrupts() is only called from irq_seq_show(), which is in
kernel/irq/proc.c as well, so build it only with CONFIG_PROC_FS, as x86
already does.

Fixes: fbb22ceaaf8f ("powerpc/irq: Make irqstats array based")
Reported-by: kernel test robot <redacted>
Closes: https://lore.kernel.org/oe-kbuild-all/202609271531.8kf2NTjK-lkp@intel.com/ (local)
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

fbb22ceaaf8f came in with bb2235894a8a ("Merge tag 'powerpc-7.4-1' of
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux"), so
mainline is affected now. Build-tested with the ppc64 randconfig from the
report, a ppc32 tinyconfig with LD_DEAD_CODE_DATA_ELIMINATION disabled
(it hides the error otherwise) and ppc64_defconfig.

 arch/powerpc/kernel/irq.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index bce546931a13b..55bcf0326f5a9 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c

@@ -122,6 +122,7 @@ void inc_irq_stat_and_enable(enum irq_stat_counts which)
 	set_bit(which, irq_stat_count_show);
 }
 
+#ifdef CONFIG_PROC_FS
 int arch_show_interrupts(struct seq_file *p, int prec)
 {
 	const struct irq_stat_info *info = irq_stat_info;

@@ -155,6 +156,7 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 #endif
 	return 0;
 }
+#endif /* CONFIG_PROC_FS */
 
 static int __init irq_init_stats(void)
 {

-- 
2.53.0