Bluetooth: Use miliseconds for L2CAP channel timeouts

Timers set by __set_chan_timer() should use miliseconds instead of
jiffies. Commit 942ecc9c updated
l2cap_set_timer() so it expects timeout to be specified in msecs
instead of jiffies. This makes timeouts unreliable when CONFIG_HZ
is not set to 1000.

Signed-off-by: Andrzej Kaczmarek <andrzej.kaczmarek@tieto.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>