V4L/DVB (12749): em28xx: remove unneeded code that set VINCTRL register

Remove redundant call to set the vinctrl register.  This eliminates any
ambiguity as to how the register is configured (since it is now always set in
em28xx_set_outfmt).

This work was sponsored by EyeMagnet Limited.

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