Revert "perf tools: event.h needs asm/perf_regs.h"

This reverts commit e083a21f.

Not needed at all, tools/perf/util/perf_regs.h, included via:

  #include "perf_regs.h"

Should have a definition for PERF_REGS_MAX, and since this is dependent
on HAVE_PERF_REGS_SUPPORT, fixes the build on powerpc, noticed by trying
to cross compile this from ubuntu16.04 with a locally build libz &
elfutils pair, since those are not available in multilib packages.

Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/n/tip-0bv204s71t4wuw1l53b6fz79@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>