Slave latency range has been changed in Core Spec. 4.2 by Erratum 5419
of ESR08_V1.0.0. And it should be applied to Core Spec. 4.0 and 4.1.

Before:
   connSlaveLatency <= ((connSupervisionTimeout / connIntervalMax) - 1)

After:
   connSlaveLatency <= ((connSupervisionTimeout / (connIntervalMax*2)) - 1)

This patch makes hci_check_conn_params() check the allowable slave
latency range using the changed way.
Signed-off-by: Seungyoun Ju <sy39.ju@samsung.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>