sfc: Remove unused mcdi functions

sfc: Remove unused mcdi functions

efx_mcdi_flush_rxqs(), efx_mcdi_rpc_async_quiet(),
efx_mcdi_rpc_finish_quiet(), and efx_mcdi_wol_filter_get_magic()
are unused.
I think these are fall out from the split into Siena
that happened in
commit 4d49e5cd4b09 ("sfc/siena: Rename functions in mcdi headers to avoid
conflicts with sfc")
and
commit d48523cb88e0 ("sfc: Copy shared files needed for Siena (part 2)")

Remove them.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Acked-by: Martin Habets <habetsm.xilinx@gmail.com>
Link: https://patch.msgid.link/20241102151625.39535-4-linux@treblig.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>