keymaster: update prototype for SymmetricKey

Remove the algorithm field as it is already
present in the 'params' list.

Change-Id: If072661081eb12fc5912d04e86e384eeb9a80f1e
diff --git a/nugget/proto/nugget/app/keymaster/keymaster_types.proto b/nugget/proto/nugget/app/keymaster/keymaster_types.proto
index c0b8b81..8224e61 100644
--- a/nugget/proto/nugget/app/keymaster/keymaster_types.proto
+++ b/nugget/proto/nugget/app/keymaster/keymaster_types.proto
@@ -84,6 +84,5 @@
 }
 
 message SymmetricKey {
-  uint32 algorithm = 1;
-  bytes material = 2;
+  bytes material = 1;
 }