x86/cpu: Implement CPU vulnerabilites sysfs functions

x86/cpu: Implement CPU vulnerabilites sysfs functions

Implement the CPU vulnerabilty show functions for meltdown, spectre_v1 and
spectre_v2.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lkml.kernel.org/r/20180107214913.177414879@linutronix.de
(cherry picked from commit 61dc0f555b5c761cdafb0ba5bd41ecf22d68a4c4)
Orabug: 27353383
Signed-off-by: Kanth Ghatraju <kanth.ghatraju@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Conflicts:
	arch/x86/Kconfig

	Resolved conflicts to pick only the changes from the patches.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>