Also set ChannelLayout to Stereo when HEAAC v2 is detected

[ChristianFeldmann]

Currently, if HEAAC v2 is detected, the number of channels is updated to 2, the ChannelPositions are updated to Front: L R but the ChannelLayout is not updated to 'L R' but shows the previously set layout of 'M'.

Before Fix:

Audio
Format                                   : AAC LC SBR PS
Format/Info                              : Advanced Audio Codec Low Complexity with Spectral Band Replication and Parametric Stereo
Commercial name                          : HE-AACv2
Format version                           : Version 4
Format settings                          : Implicit
Codec ID                                 : 2
Bit rate mode                            : Variable
Channel(s)                               : 2 channels
Channel layout                           : M
Sampling rate                            : 44.1 kHz
Frame rate                               : 21.533 FPS (2048 SPF)
Compression mode                         : Lossy
Stream size                              : 11.1 MiB (100%)

After fix:

Audio
Format                                   : AAC LC SBR PS
Format/Info                              : Advanced Audio Codec Low Complexity with Spectral Band Replication and Parametric Stereo
Commercial name                          : HE-AACv2
Format version                           : Version 4
Format settings                          : Implicit
Codec ID                                 : 2
Bit rate mode                            : Variable
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 44.1 kHz
Frame rate                               : 21.533 FPS (2048 SPF)
Compression mode                         : Lossy
Stream size                              : 11.1 MiB (100%)

[JeromeMartinez]

The channelblabla stuff deserves a full refactoring for avoiding such behavior, one day...

Thank you!