ALSA: sc6000: Fix incorrect sizeof operator

ALSA: sc6000: Fix incorrect sizeof operator

Static analysis is warning that the sizeof being used is should be
of *vport and not vport. Although these are the same size it is not
a portable assumption to assume this is true for all cases.  Fix this
by using sizeof(*vport).

Addresses-Coverity: ("Sizeof not portable")
Fixes: 111601ff76e9 ("ALSA: sc6000: Allocate resources with device-managed APIs")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210720161707.74197-1-colin.king@canonical.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>