power: perform_hint_action: return an error code

So far the caller never knows if setting the hint actually worked.
This leads to a potential disconnect between the actual setting and the
UI because set_power_profile simply assumes perform_hint_action worked.

Return an error code or 0, so the callers can check for success.

Change-Id: I180a367e9d8581a63dfa703046b37bc5cae8c6cb
Signed-off-by: Corinna Vinschen <xda@vinschen.de>
2 files changed