perf_counter tools: Fix unknown command help text

perf_counter tools: Fix unknown command help text

Arjan reported this error when entering an unknown command to perf:

  $ perf start
  fatal: Uh oh. Your system reports no Git commands at all.

The Git code expects there to be perf-* commands - but since Perf
is a 'pure' utility with no dash commands anymore, this old assumption
of Git does not hold anymore. Remove that error check.

Reported-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>