#1 MIC is incorrectly calculated

[Matt Beard]

The MICKey used to calculate the MIC is incorrectly set
and so all MICs produced are wrong.

Method HMACContext::h__HMACContext::SetKey() at line
308 of revision 1.11 of AS_DCP_AES.cpp includes this
comment:

// 7.10: MICKey = trunc( SHA1 ( key, key_nonce ) )

And indeed this is what the method does.

However, SMPTE 423M, section 7.10 actually describes
setting the MICKey as follows:

// 7.10: MICKey = trunc( HMAC-SHA1 ( key, key_nonce ) )