perf/core: Declare the __percpu attribute on non-deref types

Sparse reports the current declaration of two perf percpu variables
with this warning:

  warning: incorrect type in initializer (different address spaces)
         expected void const [noderef] <asn:3>*__vpp_verify
         got struct perf_cpu_context *<noident>

While it's normally perfectly fine to place GCC attributes anywhere
in the definition, this particular attribute is for a checking
compiler's such as Sparse's benefit, which doesn't want __percpu
on pointers.

So reorder the attribute to come after the structure type, not after
the pointer type.

[ mingo: Rewrote the changelog. ]

Signed-off-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1543310012-7967-1-git-send-email-mojha@codeaurora.org


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