Bluetooth: use recommended LE connection parameters

Bluetooth: use recommended LE connection parameters

The new connection parameters now match the recommended values for
Proximity and Health Thermometer profiles. The previous values were
ramdomly chosen, and are either too low or too high for most cases.

New values:

Scan Interval: 60 ms
Scan Window: 30 ms
Minimum Connection Interval: 50 ms
Maximum Connection Interval: 70 ms
Supervision Timeout: 420 ms

See "Table 5.2: Recommended Scan Interval and Scan Window Values" and
"Table 5.3: Recommended Connection Interval Values" for both profiles
for details. Note that the "fast connection" parameters were chosen,
because we do not support yet dynamically changing these parameters from
initiator side.

Additionally, the Proximity profile recommends (section "4.4 Alert on
Link Loss"):

"It is recommended that the Link Supervision Timeout (LSTO) is set to 6x
the connection interval."

Minimum_CE_Length and Maximum_CE_Length were also changed from 0x0001 to
0x0000 because they are informational and optional, and old value was
not reflecting reality.

Signed-off-by: Anderson Lizardo <anderson.lizardo@openbossa.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>