perf_counter: Fix ctx->mutex vs counter->mutex inversion

perf_counter: Fix ctx->mutex vs counter->mutex inversion

Simon triggered a lockdep inversion report about us taking ctx->mutex
vs counter->mutex in inverse orders. Fix that up.

Reported-by: Simon Holm Thøgersen <[email protected]>
Tested-by: Simon Holm Thøgersen <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <[email protected]>