V4L/DVB (6340): ivtvfb: screen mode change sometimes goes wrong

This patch partially reverts a previous change that caused the
CX2341X_OSD_SET_PIXEL_FORMAT firmware calls to be skipped when the pixel
format of the framebuffer wasn't altered by FBIOPUT_VSCREENINFO.

Unfortunately, another firmware call on the PVR350 sometimes scrambles the
display when trying to adjust the framebuffer settings. This patch re-enables
the CX2341X_OSD_SET_PIXEL_FORMAT calls to try and prevent this from
occurring.

Signed-off-by: Ian Armstrong <ian@iarmst.demon.co.uk>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>