media: i2c: st-vgxy61: Remove duplicate default mode set on probe

At this stage the default mode is unknown.
This is done correctly by vgxy61_fill_framefmt right after.

Signed-off-by: Benjamin Mugnier <benjamin.mugnier@foss.st.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>