[media] board-dm646x-evm.c: wrong register used in setup_vpif_input_channel_mode

The function setup_vpif_input_channel_mode() used the VSCLKDIS register
instead of VIDCLKCTL. This meant that when in HD mode videoport channel 0
used a different clock from channel 1.

Clearly a copy-and-paste error.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Manjunath Hadli <manjunath.hadli@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>