FFmpeg: Fix dsd timeline frames read calculation

[Komdosh]

This is why I'm here :)

There's a timeline glitch with DSF files when you click on the timeline.

Steps to reproduce:

• Add a .dsf (DSD) file to the playlist.
• Start playing it.
• Click the middle of the timeline.
• You'll notice the time displayed exceeds the song's duration, yet the song continues playing from the middle.

Expected behavior:

• The timeline should accurately reflect the current time.

I can't find a reason why we should do framesRead *= 8 for DSD. Looks like a mistake.