leaudio: Fix calculating needed ases

Found when testing with devices requesting two cises to single device.

Bug: 244431175
Test: atest BluetoothInstrumentationTests
Tag: #feature
Merged-In: If9d929cab8fb2275368d17aaa285403e156aea2b
Change-Id: If9d929cab8fb2275368d17aaa285403e156aea2b
(cherry picked from commit d7cf3bfc)