OPP: Pass rounded rate to _set_opp()

The OPP core finds the eventual frequency to set with the help of
clk_round_rate() and the same was earlier getting passed to _set_opp()
and that's what would get configured.

The commit 1efae8d2 ("OPP: Make dev_pm_opp_set_opp() independent of
frequency") mistakenly changed that. Fix it.

Fixes: 1efae8d2

 ("OPP: Make dev_pm_opp_set_opp() independent of frequency")
Cc: v5.18+ <stable@vger.kernel.org> # v6.0+
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>