x86/APM: Fix build warning when PROC_FS is not enabled

Fix build warning in apm_32.c when CONFIG_PROC_FS is not enabled:

../arch/x86/kernel/apm_32.c:1643:12: warning: 'proc_apm_show' defined but not used [-Wunused-function]
 static int proc_apm_show(struct seq_file *m, void *v)

Fixes: 3f3942aca6da ("proc: introduce proc_create_single{,_data}")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jiri Kosina <jikos@kernel.org>
Link: https://lkml.kernel.org/r/be39ac12-44c2-4715-247f-4dcc3c525b8b@infradead.org


diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index ec00d1f..f7151cd 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -1640,6 +1640,7 @@
 	return 0;
 }
 
+#ifdef CONFIG_PROC_FS
 static int proc_apm_show(struct seq_file *m, void *v)
 {
 	unsigned short	bx;
@@ -1719,6 +1720,7 @@
 		   units);
 	return 0;
 }
+#endif
 
 static int apm(void *unused)
 {