x86/bugs: Make cpu_show_common() static

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.

OraBug: 28041771
CVE: CVE-2018-3639

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
(cherry picked from commit 7bb4d366cba992904bffa4820d24e70a3de93e76)
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com>
 Conflicts:
	arch/x86/kernel/cpu/bugs.c
[It is called bugs_64.c]

Signed-off-by: Brian Maly <brian.maly@oracle.com>