sfc: Move and rename Falcon/Siena common NIC operations

Add efx_nic_type operations for the many efx_nic functions that need
to be implemented different on EF10.  For now, change most of the
existing efx_nic_*() functions into inline wrappers.  As a later step,
we may be able to improve branch prediction for operations used on the
fast path by copying the pointers into each queue/channel structure.

Move the Falcon/Siena implementations to new file farch.c and rename
the functions and static data to use a prefix of 'efx_farch_'.

Move efx_may_push_tx_desc() to nic.h, as the EF10 TX code will also
use it.

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

drivers/net/ethernet/sfc/Makefile

@@ -1,4 +1,5 @@
-sfc-y			+= efx.o nic.o falcon.o siena.o tx.o rx.o filter.o \
+sfc-y			+= efx.o nic.o farch.o falcon.o siena.o tx.o rx.o \
+			   filter.o \
 			   selftest.o ethtool.o qt202x_phy.o mdio_10g.o \
 			   tenxpress.o txc43128_phy.o falcon_boards.o \
 			   mcdi.o mcdi_port.o mcdi_mon.o ptp.o