Fix ScreenRecoveryUI to handle devices without power/up/down.

Currently fugu has a custom subclass to handle this. The default code
supports devices with trackballs but not all shipping Nexus devices?
That's just silly.

Change-Id: Id2779c91284899a26b4bb1af41e7033aa889df10
diff --git a/minui/events.cpp b/minui/events.cpp
index 2c41eb8..daa10c6 100644
--- a/minui/events.cpp
+++ b/minui/events.cpp
@@ -201,7 +201,7 @@
     return 0;
 }
 
-void ev_iterate_available_keys(ev_key_callback cb, void* data) {
+void ev_iterate_available_keys(std::function<void(int)> f) {
     unsigned long ev_bits[BITS_TO_LONGS(EV_MAX)];
     unsigned long key_bits[BITS_TO_LONGS(KEY_MAX)];
 
@@ -224,7 +224,7 @@
 
         for (int key_code = 0; key_code <= KEY_MAX; ++key_code) {
             if (test_bit(key_code, key_bits)) {
-                cb(key_code, data);
+                f(key_code);
             }
         }
     }