Fix smatch warning:
sound/isa/gus/gus_main.c:396 snd_gus_check_version() error:
 strcpy() 'card->longname' too large for 'card->shortname' (80 vs 32)

Even if this is not a real bug since the longest length of card->longname
now is 31, replace strcpy() with strscpy() in order to avoid possible
future mistake.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20210514070507.16600-1-yuehaibing@huawei.comSigned-off-by: Takashi Iwai <tiwai@suse.de>