IOS: Reuse more code for crypto operations

This changes some parts of IOS (actually just ES) to reuse more crypto
code from IOSC or Common::AES.

TicketReader still returns the title key directly as opposed to having
ES use IOSC directly to avoid duplicating the title key IV stuff.

Side effects:

* A nasty unbounded array access bug is now fixed.

* ES_Decrypt/ES_Encrypt now returns sane results for keys other than
  the SD key.

* Titles with a Korean ticket can now be decrypted properly.

And in the future, we can look into implementing ioctlv 0x3c and 0x3d
now that we have the proper "infra" for IOSC calls.

Source/Core/Core/ec_wii.cpp

@@ -9,7 +9,6 @@
 
 #include "Core/ec_wii.h"
 
-#include <algorithm>
 #include <cstdio>
 #include <cstring>
 
@@ -180,19 +179,6 @@ const u8* EcWii::GetNGSig() const
   return BootMiiKeysBin.ng_sig;
 }
 
-std::array<u8, 16> EcWii::GetSharedSecret(const EcWii::ECCKey& peer_public_key) const
-{
-  EcWii::ECCKey shared_secret;
-  point_mul(shared_secret.data(), GetNGPriv(), peer_public_key.data());
-
-  std::array<u8, 20> sha1;
-  mbedtls_sha1(shared_secret.data(), shared_secret.size() / 2, sha1.data());
-
-  std::array<u8, 16> aes_key;
-  std::copy_n(sha1.cbegin(), aes_key.size(), aes_key.begin());
-  return aes_key;
-}
-
 void EcWii::InitDefaults()
 {
   memset(&BootMiiKeysBin, 0, sizeof(BootMiiKeysBin));