media: ti: davinci: vpbe_display.c: return 0 instead of 'ret'.

Since 'ret' is known to be 0, just return '0'. This fixes a smatch warning:

vpbe_display.c:1152 vpbe_display_open() warn: missing error code? 'err'

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>