idr_get_new*() and friends are about to be deprecated. Convert to the
new idr_alloc() interface.
There are some peculiarities and possible bugs in the converted
functions. This patch preserves those.
* drv_insert_node_res_element() returns -ENOMEM on alloc failure,
-EFAULT if id space is exhausted. -EFAULT is at best misleading.
* drv_proc_insert_strm_res_element() is even weirder. It returns
-EFAULT if kzalloc() fails, -ENOMEM if idr preloading fails and
-EPERM if id space is exhausted. What's going on here?
* drv_proc_insert_strm_res_element() doesn't free *pstrm_res after
failure.