Bluetooth: SCO: Fix not validating setsockopt user input

syzbot reported sco_sock_setsockopt() is copying data without
checking user input length.

BUG: KASAN: slab-out-of-bounds in copy_from_sockptr_offset
include/linux/sockptr.h:49 [inline]
BUG: KASAN: slab-out-of-bounds in copy_from_sockptr
include/linux/sockptr.h:55 [inline]
BUG: KASAN: slab-out-of-bounds in sco_sock_setsockopt+0xc0b/0xf90
net/bluetooth/sco.c:893
Read of size 4 at addr ffff88805f7b15a3 by task syz-executor.5/12578

Fixes: ad10b1a4 ("Bluetooth: Add Bluetooth socket voice option")
Fixes: b96e9c67 ("Bluetooth: Add BT_DEFER_SETUP option to sco socket")
Fixes: 00398e1d ("Bluetooth: Add support for BT_PKT_STATUS CMSG data for SCO connections")
Fixes: f6873401 ("Bluetooth: Allow setting of codec for HFP offload use case")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>