Bluetooth: Add sockopts for LE Connection Params

Various LE profiles require very specific LE parameters for
both establishing and maintaining LE connections to remote
peripherals. These LE only parameters are encapsulated into
a single sockopts structure, and may be passed from user space.

CRs-Fixed: 335971
Change-Id: I408edb97ab0fa9717c7d3fe5fc8ad6ac179a2fff
Signed-off-by: Brian Gix <bgix@codeaurora.org>