perf report/tui: Fix a bug when --fields/sort is given

perf report/tui: Fix a bug when --fields/sort is given

The hists__filter_entries() function is called when down arrow key is
pressed for navigating through the entries in TUI.  It has a check for
filtering out entries that have very small overhead (under min_pcnt).

However it just assumed the entries are sorted by the overhead so when
it saw such a small overheaded entry, it just stopped navigating as an
optimization.  But it's not true anymore due to new --fields and
--sort optoin behavior and this case users cannot go down to a next
entry if ther's an entry with small overhead in-between.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1400480762-22852-14-git-send-email-namhyung@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>