Bluetooth: Audio: Increase PA sync timeouts

Increase the timeouts to be 60 instead of 6.
The reason for this is that some controllers (like the Zephyr
controller) will reserve some of these to ensure stability,
and in fact with skip = 5 and retry = 6, it would still
send the PA reports at every interval.

To accomodate a higher timeout value, the functions used to
convert PA intervals to PA timeouts have been updated.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>