x86/bugs: Concentrate bug detection into a separate function

x86/bugs: Concentrate bug detection into a separate function

Combine the various logic which goes through all those
x86_cpu_id matching structures in one function.

OraBug: 28041771
CVE: CVE-2018-3639

Suggested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 4a28bfe3267b68e22c663ac26185aa16c9b879ef)
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Mihai Carabas <mihai.carabas@oracle.com>
 Conflicts:
	arch/x86/kernel/cpu/common.c

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