Bluetooth: Add MGMT Shorter Connection Interval setting

Add MGMT_SETTING_SCI (bit 25) to advertise support for the Shorter
Connection Interval (SCI) feature. It is reported in the supported
settings whenever the controller is SCI capable, and in the current
settings whenever LE is enabled and the controller is SCI capable
(SCI has no separate enable command, so it is a passive capability).

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>