CryptoPkg/BaseCryptLib: Retire HMAC MD5 algorithm

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1898

HMAC MD5 is not secure any longer.
Remove the HMAC MD5 support from edk2.
Change the HMAC MD5 field name in EDKII_CRYPTO_PROTOCOL to indicate the
function is unsupported any longer.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Xiaoyu Lu <xiaoyux.lu@intel.com>
Cc: Siyuan Fu <siyuan.fu@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Philippe Mathieu-Daude <philmd@redhat.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>
Signed-off-by: Zhichao Gao <zhichao.gao@intel.com>

CryptoPkg/Library/BaseCryptLibNull/BaseCryptLibNull.inf

@@ -34,7 +34,6 @@
   Hash/CryptSha256Null.c
   Hash/CryptSha512Null.c
   Hash/CryptSm3Null.c
-  Hmac/CryptHmacMd5Null.c
   Hmac/CryptHmacSha1Null.c
   Hmac/CryptHmacSha256Null.c
   Kdf/CryptHkdfNull.c