net/sfc/base: enable chained multicast on all EF10 cards

net/sfc/base: enable chained multicast on all EF10 cards

Set WORKAROUND_BUG26807 which does the job.

Fix the misunderstanding in the Medford code: i.e. the workaround is
always supported by firmware, but the driver still needs to enable it.
Also, as it now applies to all EF10 controllers, the implementation is
moved to EF10 common place.

Fixes: 94190e3543bf ("net/sfc/base: import SFN8xxx family support")
Fixes: 2b38e7b7b7e1 ("net/sfc/base: add Medford2 support to NIC module")
Cc: stable@dpdk.org
Signed-off-by: Gautam Dawar <gdawar@solarflare.com>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>