LE Create Connection command timeout increased to 20 secs

On our DUT, we can see that the host issues create connection cancel
command after 4-sec if there is no connection complete event for
LE create connection cmd.
As per core spec v5.3 section 7.8.5, advertisement interval range is-

Advertising_Interval_Min
Default : 0x0800(1.28s)
Time Range: 20ms to 10.24s

Advertising_Interval_Max
Default : 0x0800(1.28s)
Time Range: 20ms to 10.24s

If the remote device is using adv interval of > 4 sec, it is
difficult to make a connection with the current timeout value.
Also, with the default interval of 1.28 sec, we will get only
3 chances to capture the adv packets with the 4 sec window.
Hence we want to increase this timeout to 20sec.

Signed-off-by: Mahesh Talewad <mahesh.talewad@nxp.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>