Bluetooth: fix unaligned access to l2cap conf data

In function l2cap_get_conf_opt() and l2cap_add_conf_opt() the address of
opt->val sometimes is not at the edge of 2-bytes/4-bytes, so 2-bytes/4 bytes
access will cause data misalignment exeception.  Use get_unaligned_le16/32
and put_unaligned_le16/32 function to avoid data misalignment execption.

Signed-off-by: steven miao <realmz6@gmail.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>