net/sfc: do not hold management event queue lock while MCDI

net/sfc: do not hold management event queue lock while MCDI

MCDI execution may require MCDI proxy handling which involves
management event queue polling. So, it is a bad idea to hold
managment event queue lock when MCDI is executed.

Event queue creation and destruction are MCDI operations.

Fixes: 4650ed44c120 ("net/sfc: support MCDI proxy")
Cc: stable@dpdk.org
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Ivan Malov <ivan.malov@oktetlabs.ru>
Reviewed-by: Andy Moreton <amoreton@solarflare.com>