Remove "required" label from DSA algorithm.

Change-Id: I088e6094ec56f434356d11ab2032b1a5b1223334
diff --git a/include/hardware/keymaster_defs.h b/include/hardware/keymaster_defs.h
index 95ffe8e..b351aa4 100644
--- a/include/hardware/keymaster_defs.h
+++ b/include/hardware/keymaster_defs.h
@@ -187,7 +187,7 @@
 typedef enum {
     /* Asymmetric algorithms. */
     KM_ALGORITHM_RSA = 1,   /* required */
-    KM_ALGORITHM_DSA = 2,   /* required */
+    KM_ALGORITHM_DSA = 2,
     KM_ALGORITHM_ECDSA = 3, /* required */
     KM_ALGORITHM_ECIES = 4,
     /* FIPS Approved Ciphers */