Bluetooth: Set le data length command and event

Bluetooth: Set le data length command and event

Sets the data length for the le data packet with in the
advised limits. MGMT command and event are added to handle
the setting of data length.

Change-Id: Ib99d8175abbc9a16522870a3871f42527013a0cb
Signed-off-by: Sudha Bheemanna <b.sudha@samsung.com>
Signed-off-by: Amit Purwar <amit.purwar@samsung.com>
Signed-off-by: DoHyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: Wootak Jung <wootak.jung@samsung.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>