perf hists: Allow limiting the number of rows and columns in fprintf

So that we can reuse hists__fprintf for in the new perf top tool.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-huazw48x05h8r9niz5cf63za@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>