perf evlist: Remove extraneous 'was' on error message

perf evlist: Remove extraneous 'was' on error message

  [acme@mica ~]$ trace -p 3330
  Error:  Unable to find debugfs
  Hint:   Was your kernel was compiled with debugfs support?
                          ^^^
                          ^^^
  Hint:   Is the debugfs filesystem mounted?
  Hint:   Try 'sudo mount -t debugfs nodev /sys/kernel/debug'

Fix it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-kb9s0xy5z8i51abdu4bgm3rv@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>