net/sfc/base: import MCDI proxy authorization

net/sfc/base: import MCDI proxy authorization

MCDI proxy authorization may be used if privileged PCI
function (physical function) would like to intercept and
authorize MCDI requests done by unprivileged (e.g. virtual)
PCI function. It may be used to control unprivileged
function Rx mode (e.g. promiscuous, all-multicast), MTU
and default MAC address change requests etc.

Current libefx support is limited to client-side which
is required to work when function requests need to be
authorized.

Server side support required to request and do the
authorization is not implemented yet.

EFSYS_OPT_MCDI_PROXY_AUTH should be enabled to use it.

From Solarflare Communications Inc.

Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>