net/ena: lock dynamic usages of admin queue

net/ena: lock dynamic usages of admin queue

There are some cases, where the admin queue commands after the
configuration phase finished - for example, the application could ask
for the driver statistics from multiple cores at once.

As by the design, the admin queue is not multithread safe, the spinlock
was added to protect all usages of the admin queue after the
configuration is done.

Signed-off-by: Michal Krawczyk <mk@semihalf.com>
Reviewed-by: Igor Chauskin <igorch@amazon.com>
Reviewed-by: Guy Tzalik <gtzalik@amazon.com>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>