Bluetooth: Check for minimum data length in eir_has_data_type()

If passed 0 as data_length the (parsed < data_length - 1) test will be
true and cause a buffer overflow. In practice we need at least two bytes
for the element length and type so add a test for it to the very
beginning of the function.

Signed-off-by: Johan Hedberg <[e-mail]>
Acked-by: Marcel Holtmann <[e-mail]>
Signed-off-by: Gustavo Padovan <[e-mail]>

include/net/bluetooth/hci_core.h

···
 {
 	size_t parsed = 0;
 
+	if (data_len < 2)
+		return false;
+
 	while (parsed < data_len - 1) {
 		u8 field_len = data[0];