power: Refactor TARGET_TAP_TO_WAKE_NODE

Add TARGET_POWER_SET_FEATURE_LIB, since other devices
are not simply writing a 0/1 to a device node.
TARGET_TAP_TO_WAKE_NODE is still valid and both
TARGET_TAP_TO_WAKE_NODE and TARGET_POWER_SET_FEATURE_LIB are
allowed to coexist. (Currently set_feature only has double tap
to wake, but it may be extended in future)

Change-Id: I5c6204fd38a6fbe48e8aac49843bfa047c4b6436
diff --git a/Power.cpp b/Power.cpp
index ebdc60a..2caeaca 100644
--- a/Power.cpp
+++ b/Power.cpp
@@ -33,6 +33,7 @@
 #include <log/log.h>
 #include "Power.h"
 #include "power-common.h"
+#include "power-feature.h"
 
 namespace android {
 namespace hardware {
@@ -74,6 +75,7 @@
         default:
             break;
     }
+    set_device_specific_feature(static_cast<feature_t>(feature), activate ? 1 : 0);
     return Void();
 }