drm/i2c: tda998x: always disable and clear interrupts at probe

Always disable and clear interrupts at probe time to ensure that the
TDA998x is in a sane state.  This ensures that the interrupt line,
which is also the CEC clock calibration signal, is always deasserted.

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