Remove the check for epskc flag value at runtime.

This blocks local testing as the flag is read-only.

Change-Id: I891ef2d61dbb1ecccde7b89081899afb7155dd2f
diff --git a/thread/framework/java/android/net/thread/ThreadNetworkController.java b/thread/framework/java/android/net/thread/ThreadNetworkController.java
index bcef76c..14d22d1 100644
--- a/thread/framework/java/android/net/thread/ThreadNetworkController.java
+++ b/thread/framework/java/android/net/thread/ThreadNetworkController.java
@@ -423,11 +423,6 @@
                 @EphemeralKeyState int ephemeralKeyState,
                 String ephemeralKey,
                 long lifetimeMillis) {
-            if (!Flags.epskcEnabled()) {
-                throw new IllegalStateException(
-                        "This should not be called when Ephemeral key API is disabled");
-            }
-
             final long identity = Binder.clearCallingIdentity();
             final Instant expiry =
                     ephemeralKeyState == EPHEMERAL_KEY_DISABLED