V4L/DVB (3344b): don't ignore return from i2c_add_driver() for tuner-3036


The call to i2c_add_driver() may actually fail, but tuner-3036 ignores
this and always returns 0, regardless.

Fix it up so it returns what i2c_add_driver() does, instead.

Signed-off-by: Arthur Othieno <a.othieno@bluewin.ch>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>