phone: Use maximum cpu frequency

Seems to be a bit more unstable but the performance difference is huge
enough that I'd rather run this than the minimum cpu frequency.

Battery life seems to be okay with around 3 hours of on-screen time and
low brightness. The massive increase in performance means that there's
much less time spent waiting for the phone, so the decrease in on-screen
time should be offset by how long you have to keep the phone on waiting
for it.

hosts/phone/configuration.nix

@@ -200,10 +200,10 @@ in
     enable = true;
 
     cpufreq = rec {
-      min = 648000;
+      min = 1152000;
       max = min;
     };
 
-    cpuFreqGovernor = "powersave";
+    cpuFreqGovernor = "performance";
   };
 }