Remove unused using.

Test: TH
Bug: 186266747
Change-Id: I4c382071fa8b098680f8350ddc7ffd196a7f61f6
diff --git a/ondevice-signing/Keymaster.cpp b/ondevice-signing/Keymaster.cpp
index 6cfb565..f9bf9b2 100644
--- a/ondevice-signing/Keymaster.cpp
+++ b/ondevice-signing/Keymaster.cpp
@@ -45,7 +45,6 @@
 using android::sp;
 using android::base::Error;
 using android::base::Result;
-using android::base::unique_fd;
 using android::hardware::hidl_vec;
 
 Keymaster::Keymaster() {}
diff --git a/ondevice-signing/KeystoreKey.cpp b/ondevice-signing/KeystoreKey.cpp
index 96e369a..4e59c58 100644
--- a/ondevice-signing/KeystoreKey.cpp
+++ b/ondevice-signing/KeystoreKey.cpp
@@ -51,8 +51,6 @@
 using android::base::Error;
 using android::base::Result;
 
-using android::base::unique_fd;
-
 // Keystore boot level that the odsign key uses
 static const int kOdsignBootLevel = 30;