ALSA: seq: replace ternary operator with max()

Fix the following coccicheck warning:

sound/core/seq/seq_ports.c:142:12-14: WARNING opportunity for max()

Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Link: https://lore.kernel.org/r/20220517062518.123292-1-guozhengkui@vivo.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>