x86/bugs: Make cpu_show_common() static

cpu_show_common() is not used outside of arch/x86/kernel/cpu/bugs.c, so
make it static.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/cpu/bugs.c

@@ -640,7 +640,7 @@ void x86_spec_ctrl_setup_ap(void)
 
 #ifdef CONFIG_SYSFS
 
-ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
+static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
 			char *buf, unsigned int bug)
 {
 	if (!boot_cpu_has_bug(bug))