SecurityPkg/TPM2: Move GetDigestFromDigestList() to Tpm2CommandLib

This patch just moves function Tpm2GetDigestFromDigestList() from
drivers to library as GetDigestFromDigestList() and no functionality change.

Cc: Chao B Zhang <chao.b.zhang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>

SecurityPkg/Library/Tpm2CommandLib/Tpm2Help.c

@@ -1,7 +1,7 @@
 /** @file
   Implement TPM2 help.
 
-Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved. <BR>
+Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved. <BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
@@ -164,3 +164,39 @@ CopyAuthSessionResponse (
 
   return (UINT32)(UINTN)(Buffer - (UINT8 *)AuthSessionIn);
 }
+
+/**
+  This function get digest from digest list.
+
+  @param HashAlg    digest algorithm
+  @param DigestList digest list
+  @param Digest     digest
+
+  @retval EFI_SUCCESS   Sha1Digest is found and returned.
+  @retval EFI_NOT_FOUND Sha1Digest is not found.
+**/
+EFI_STATUS
+EFIAPI
+GetDigestFromDigestList (
+  IN TPMI_ALG_HASH      HashAlg,
+  IN TPML_DIGEST_VALUES *DigestList,
+  IN VOID               *Digest
+  )
+{
+  UINTN  Index;
+  UINT16 DigestSize;
+
+  DigestSize = GetHashSizeFromAlgo (HashAlg);
+  for (Index = 0; Index < DigestList->count; Index++) {
+    if (DigestList->digests[Index].hashAlg == HashAlg) {
+      CopyMem (
+        Digest,
+        &DigestList->digests[Index].digest,
+        DigestSize
+        );
+      return EFI_SUCCESS;
+    }
+  }
+
+  return EFI_NOT_FOUND;
+}