perf top/tui: Update nr_entries properly after a filter is applied

The hist_browser__reset() is only called right after a filter is
applied so it needs to udpate browser->nr_entries properly.  We cannot
use hists->nr_non_filtered_entreis directly since it's possible that
such entries are also filtered out by minimum percentage limit.

In addition when a filter is used for perf top, hist browser's
nr_entries field was not updated after applying the filter.  But it
needs to be updated as new samples are coming.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1398327843-31845-11-git-send-email-namhyung@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>