drm/i2c: tda998x: move mutex/waitqueue/timer/work init early

Move the mutex, waitqueue, timer and detect work initialisation early
in the driver's initialisation, rather than being after we've registered
the CEC device.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>