perf/x86: Fix Userspace RDPMC switch

The current code forgets to change the CR4 state on the current CPU.
Use on_each_cpu() instead of smp_call_function().

Reported-by: Mark Davies <junk@eslaf.co.uk>
Suggested-by: Mark Davies <junk@eslaf.co.uk>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: fweisbec@gmail.com
Link: http://lkml.kernel.org/n/tip-69efsat90ibhnd577zy3z9gh@git.kernel.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>