drivers: hci: ipc: Make IPC endpoint bound timeout configurable

The HCI IPC endpoint bound timeout value was hardcoded and set
to 1000 ms. This value may be differ between platforms, for
exampel due to extended boot time.
The default value used was a bit short for multicore SoCs
that usually may wait for some other service reposnes for
similar time. That may lead to timeout error while other
end of an endpoint was slightly late. Change the default
duration to 2000 ms to give more room for possible delays.

Signed-off-by: Piotr Pryga <piotr.pryga@nordicsemi.no>