V4L/DVB (6995): ubvision: add adjust_X_Offset/adjust_Y_Offset parms

Add adjust_X_Offset/adjust_Y_Offset module parameters to allow users
to tune X and Y picture offsets for their almost-working tuners without
repetitive recompilation.

Signed-off-by: Thierry MERLE <thierry.merle@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>