Keymaster memory management is inconsistent

Objects derived from RefBase should always be owned by sp rather then
unique_ptr or other smart pointer implementations.

Bug: 79474587
Change-Id: I6a3ca04b3a3bab74c6114643ffdaeac537188d12

Android.bp

@@ -230,6 +230,7 @@ cc_binary {
         "libhidlbase",
         "libhwbinder",
         "libkeymaster4support",
+        "libutils",
     ],
 }
 

Keymaster.h

@@ -115,7 +115,7 @@ class Keymaster {
     bool isSecure();
 
   private:
-    std::unique_ptr<KmDevice> mDevice;
+    sp<KmDevice> mDevice;
     DISALLOW_COPY_AND_ASSIGN(Keymaster);
     static bool hmacKeyGenerated;
 };