Panic on linux when advertisementData has a length of 255

[EthanYidong]

panic: runtime error: slice bounds out of range [2:0]

How to reproduce: Run the discoverer.go example, and have some BLE device nearby that has a 255 byte-long advertisement data, so that

gatt/adv.go

Lines 2008 to 2013 in df6e615

	l, t := b[0], b[1]
	if int(l) < 1 || len(b) < int(1+l) {
	return errors.New("invalid advertise data")
	}
	d := b[2 : 1+l]

causes 1 + l to overflow to 0.

I also received this error from the ble.recon bettercap module.

Fixes: I am not familiar with the bluetooth spec, so I am not sure if such a length is valid. Nor am I sure what device was causing the error.
If this is not standard and should not be allowed, then adding a check and returning an error would solve the problem. Otherwise, l, t := uint(b[0]), b[1] prevents the overflow.