PM / devfreq: governor_cpufreq: Fix incorrect refcounting of OF node

The of_node_put(of_child) call was put in to balance the of_node_get()
that's done inside for_each_child_of_node(). But that's not the right thing
to do because for_each_child_of_node() already takes care of doing
of_node_put(). So, delete the unnecessary of_node_put(of_child) call. We
still need the of_node_put(of_par) though.

Change-Id: Iff7744839cfcf01d5a472449f74859e9030b7e16
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>