ncm: add error check and retry mechanism for gcom call

ncm: add error check and retry mechanism for gcom call

This patch solves the problem of receiving "error" responses when
initially calling gcom. This avoids unnecessary NO_DEVICE failures.

A retry loop retries the call after an "error" response within the
specified delay. A successful response will continue with the connection
immediately without waiting for max specified delay, bringing the
interface up sooner.

Signed-off-by: Mike Wilson <mikewse@hotmail.com>
(cherry picked from commit 8f27093ce784daad5a9b1c89f51d0a76a8bbb07b)