LeAudio: Fix not respecting preferred presentation delay

In a corner case when preferred delay min was equal to preferred delay
max and at the same time equal to delay_max, we by mistake were
using delay_min instead of the preferred value that was still in the
<min,max> range.

Bug: 383623629
Test: atest bluetooth_le_audio_test
Flag: Exempt; day-to-day bugfix
Change-Id: Ibcde45ac3b60c7a248e1b1e4b87299daf6783f2d