sfc: Make efx_mcdi_{init,fini}() call efx_mcdi_drv_attach()

This should be done during MCDI initialisation for any NIC.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

diff --cc drivers/net/ethernet/sfc/mcdi.c
Simple merge

diff --cc drivers/net/ethernet/sfc/mcdi.h
Simple merge

diff --cc drivers/net/ethernet/sfc/siena.c
Simple merge