Remove notification for update process timeout.

[zacwbond]

(This addresses issue #780, just like PR #781, which was closed due to some repo juggling on my end.)

From the original

This is a fix for #780, an issue I submitted earlier today.

I am connecting as a central to a remote peripheral using a connection interval of 120, latency of 90, and timeout of 3000. Due to the hard-coded 40 second timeout, it is impossible to perform a connection parameter update on this connection. Trying to do so results in a timeout followed by a disconnect 100% of the time.

My attempt to fix the problem is to compute the timeout based on the current connection parameters instead of just hard-coding a constant value.

Based on @rymanluk's comments to that PR, I have reduced the change to keeping the 40s timeout, but simply not posting an event should a timeout occur.

[rymanluk]

Looks good to me, we just need better commit message here :)

1. Please add nimble/gap: prefix to the commit title
2. In commit message body please write why we are removing it.

[rymanluk]

Thanks for updating commit message.

Could you please change it to following (also please try keep max 80 chars per line):

"The connection parameter update process has a hard-coded 40-second timeout,
but in reality, the time it takes to complete a connection parameter might take longer, as it
depends on the connection interval and when controller deciders to do it.
This patch changes meaning of this 40 sec timer to be only a guard so the application
does not perform too many connection update parameter requests.
Now when timeout fires, application will not be notified about that and link will not be dropped."

As you can see also Travis complains on this patch. Please check details.
You can reproduce the problem by running unit test on your PC

"newt test @apache-mynewt-nimble/nimble/host/test"

To solve it please remove ble_gap_test_util_update_no_l2cap_tmo function as we don't need it anymore.

[apache-mynewt-bot]

Style check summary

No suggestions at this time!

[rymanluk]

Thanks. lgtm