Bluetooth: hci_le_adv_report_evt code refactoring

There is no reason to treat the first advertising entry differently
from the potential other ones. Besides, the current implementation
can easily leads to typos.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>