x86, lib: Add wbinvd smp helpers

Add wbinvd_on_cpu and wbinvd_on_all_cpus stubs for executing wbinvd on a
particular CPU.

[ hpa: renamed lib/smp.c to lib/cache-smp.c ]
[ hpa: wbinvd_on_all_cpus() returns int, but wbinvd() returns
  void.  Thus, the former cannot be a macro for the latter,
  replace with an inline function. ]

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <1264172467-25155-2-git-send-email-bp@amd64.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index cffd754f..d85e0e4 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -14,7 +14,7 @@
 
 clean-files := inat-tables.c
 
-obj-$(CONFIG_SMP) += msr-smp.o
+obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o
 
 lib-y := delay.o
 lib-y += thunk_$(BITS).o