net: smc911x: replace ternary operator with min()

Fix the following coccicheck warning:

drivers/net/ethernet/smsc/smc911x.c:483:20-22: WARNING opportunity for min()

Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Link: https://lore.kernel.org/r/20220516115627.66363-1-guozhengkui@vivo.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>