regmap: Initialize `map->debugfs' before regcache

regmap: Initialize `map->debugfs' before regcache

commit c6432ea9cc043994d5b7dcb3ad86a087777cb40c upstream.

In the rbtree code we are exposing statistics relating to the
number of nodes/registers of the rbtree cache for each of the
devices.  Ensure that `map->debugfs' has been initialized before
we attempt to initialize the debugfs entry for the rbtree cache.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>