opp: Add dev_pm_opp_find_level_ceil()

Add a ceil version of the dev_pm_opp_find_level(). It's handy to have if
levels don't start from 0 in OPP table and zero usually means a minimal
level.

Tested-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Tested-by: Matt Merhar <mattmerhar@protonmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>