Remove note from CHANGES about EC DRBG

EC DRBG support was added in 7fdcb457 in 2011 and then later removed.
However the CHANGES entry for its original addition was left behind.
This just removes the spurious CHANGES entry.
Reviewed-by: NStephen Henson <steve@openssl.org>

CHANGES

@@ -878,10 +878,6 @@
      combination: call this in fips_test_suite.
      [Steve Henson]
 
-  *) Add support for Dual EC DRBG from SP800-90. Update DRBG algorithm test
-     and POST to handle Dual EC cases.
-     [Steve Henson]
-
   *) Add support for canonical generation of DSA parameter 'g'. See 
      FIPS 186-3 A.2.3.