V4L/DVB (12880): em28xx: fix codingstyle issues introduced with VBI support

Fix a few codingstyle issues introduced when I was adding the VBI support to
the em28xx driver.

Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>