These log messages are wrong because _of_get_opp_desc_node() returns
an operating-points-v2 node.

Commit a6eed752 ("PM / OPP: passing NULL to PTR_ERR()") fixed
static checker warnings, and reworded the messages at the same time
(but the latter was not mentioned in the git-log).

Restore the correct messages.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NViresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>