OPP: Add dev_pm_opp_set_level()

To configure a device to a specific performance level, consumer drivers
currently need to determine the OPP based on the exact level and then
set it, resulting in code duplication across drivers.

The new helper API, dev_pm_opp_set_level(), addresses this issue by
providing a streamlined method for consumer drivers to find and set the
OPP based on the desired performance level, thereby eliminating
redundancy.

Signed-off-by: Praveen Talari <quic_ptalari@quicinc.com>
[ Viresh: Lot of fixes in the code, and rebased over latest changes.
           Fixed commit log too. ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>