perf map: Remove extra indirection from map__find()

A double pointer is used in map__find() where a single pointer is enough
because the function doesn't affect the rbtree and the rbtree is locked.

Signed-off-by: Eric Saint-Etienne <eric.saint.etienne@oracle.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Eric Saint-Etienne <eric.saintetienne@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1542969759-24346-1-git-send-email-eric.saint.etienne@oracle.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>