ALSA: seq: remove redundant unsigned comparison to zero

Since struct snd_ump_block_info::first_group is unsigned char, comparison
to zero is redundant

Signed-off-by: Wang Weiyang <wangweiyang2@huawei.com>
Fixes: 81fd444a ("ALSA: seq: Bind UMP device")
Link: https://lore.kernel.org/r/20230721103124.18522-1-wangweiyang2@huawei.com


Signed-off-by: Takashi Iwai <tiwai@suse.de>