drivers: wifi: simplelink: add timeout for fast connect feature

The SimpleLink wifi driver enables the Fast Connect method of
WiFi provisioning, which allows the network coprocessor to
reconnect to a previously connected Access Point (AP) on
startup.

Previously, if Fast Connect failed to connect, any network
socket applications would inevitably fail, as there would have
been no wifi connection.

This patch adds a configurable timeout for the Fast Connect
feature, after which timeout, an error is logged informing
the user to manually reconnect to an AP.

Reconnection is typically accomplished by separately running the
wifi sample shell program.

Fixes: #11889

Signed-off-by: Gil Pitney <gil.pitney@linaro.org>