lockdep: Fix trace_hardirqs_on_caller()

lockdep: Fix trace_hardirqs_on_caller()

Commit dd4e5d3ac4a ("lockdep: Fix trace_[soft,hard]irqs_[on,off]()
recursion") made a bit of a mess of the various checks and error
conditions.

In particular it moved the check for !irqs_disabled() before the
spurious enable test, resulting in some warnings.

Reported-by: Arnaud Lacombe <[email protected]>
Reported-by: Dave Jones <[email protected]>
Reported-and-tested-by: Sergey Senozhatsky <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/1311679697.24752.28.camel@twins
Signed-off-by: Ingo Molnar <[email protected]>