V4L/DVB (12466): Kconfig files: Fix improper use of whitespaces

On VIDEO_M52790 and USB_GSPCA_SN9C20X, instead of tab, it were
using 7 whitespaces at the beginning, probably due to some
cut-and-paste trouble.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>