Fix crypto/des/build.info

!$disabled{mdc2} was used to determine if DES files should be included
in providers/liblegacy.a.  Use !$disabled{des} instead.

Fixes #13865

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/13866)

crypto/des/build.info

@@ -31,7 +31,7 @@ DEFINE[../../providers/liblegacy.a]=$DESDEF
 
 # When all deprecated symbols are removed, libcrypto doesn't export the
 # DES functions, so we must include them directly in liblegacy.a
-IF[{- $disabled{'deprecated-3.0'} && !$disabled{"mdc2"} -}]
+IF[{- $disabled{'deprecated-3.0'} && !$disabled{des} -}]
   SOURCE[../../providers/liblegacy.a]=$ALL
   DEFINE[../../providers/liblegacy.a]=$DESDEF
 ENDIF