[build] Mark MS-CHAPv2 as permitted for UEFI Secure Boot

MS-CHAPv2 and the underlying DES algorithm are cryptographically
obsolete, but still relatively widely used.  There is no impact to
UEFI Secure Boot from using these obsolete algorithms: the only
untrusted inputs are the username, password, and received network
packets, and all of these are thoroughly validated before use.

Review these files and mark them as permitted for UEFI Secure Boot.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/crypto/des.c

@@ -22,6 +22,7 @@
  */
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+FILE_SECBOOT ( PERMITTED );
 
 /** @file
  *

src/crypto/mschapv2.c

@@ -22,6 +22,7 @@
  */
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+FILE_SECBOOT ( PERMITTED );
 
 /** @file
  *

src/include/ipxe/des.h

@@ -8,6 +8,7 @@
  */
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+FILE_SECBOOT ( PERMITTED );
 
 #include <ipxe/crypto.h>
 

src/include/ipxe/mschapv2.h

@@ -8,6 +8,7 @@
  */
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+FILE_SECBOOT ( PERMITTED );
 
 #include <stdint.h>
 

src/net/eap_mschapv2.c

@@ -22,6 +22,7 @@
  */
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+FILE_SECBOOT ( PERMITTED );
 
 #include <stdlib.h>
 #include <string.h>