drivers: thermal: tsens: De-constify struct tsens_features

struct tsens_features is currently initialized as part of platform data
at compile-time and not modifiable. We now have some usecases in feature
detection across IP versions where it is more flexible to update the
features after probing registers.

Remove const qualifier from tsens_features and the encapsulating
tsens_plat_data.

Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/2919a72220470366ae11e0bb5330a4ea39838f71.1584015867.git.amit.kucheria@linaro.org