UPSTREAM: powercap/drivers/dtpm: Add the experimental label to the option description

The DTPM framework will evolve in the next cycles. Let's add a
temporary EXPERIMENTAL tag to the option so users will be aware
the API may change over time.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Link:
https://patchwork.kernel.org/project/linux-pm/patch/20210224183022.11846-2-daniel.lezcano@linaro.org/


Bug: 183374898
Change-Id: Icb0000fcc36ccac1f1166bbdc2a991a53cc67a2e
(cherry picked from commit 9e2be308)
Signed-off-by: Ram Chandrasekar <quic_rkumbako@quicinc.com>