perf annotate browser: The idx_asm field should be used in asm only view

perf annotate browser: The idx_asm field should be used in asm only view

When hide_src_view is true we can't use browser_disasm_line->idx, that
takes into account also non asm lines, we must use browser_disasm_line->idx_asm
instead, otherwise we may end up with an index after the number of
entries, oops, fix it.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
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-o1szpyjh3z87yi0n6x0cr8uu@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>