PM / Domains: Drop comment in genpd about legacy Samsung DT binding

The parsing of the Samsung specific DT binding is gone, but the comment in
the function header remained. Let's drop the comment to avoid confusions.

Fixes: 001d50c9 (PM / Domains: Remove obsolete "samsung,power-domain" check)
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>