net: macb: fixup sparse warnings on __be16 ports

net: macb: fixup sparse warnings on __be16 ports

The port fields in the ethool flow structures are defined
to be __be16 types, so sparse is showing issues where these
are being passed to htons(). Fix these warnings by passing
them to be16_to_cpu() instead.

These are being used in netdev_dbg() so should only effect
anyone doing debug.

Fixes the following sparse warnings:

drivers/net/ethernet/cadence/macb_main.c:3366:9: warning: cast from restricted __be16
drivers/net/ethernet/cadence/macb_main.c:3366:9: warning: cast from restricted __be16
drivers/net/ethernet/cadence/macb_main.c:3366:9: warning: cast from restricted __be16
drivers/net/ethernet/cadence/macb_main.c:3419:25: warning: cast from restricted __be16
drivers/net/ethernet/cadence/macb_main.c:3419:25: warning: cast from restricted __be16
drivers/net/ethernet/cadence/macb_main.c:3419:25: warning: cast from restricted __be16
drivers/net/ethernet/cadence/macb_main.c:3419:25: warning: cast from restricted __be16

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>
Link: https://lore.kernel.org/r/20220715173009.526126-1-ben.dooks@sifive.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>