drm/i2c: tda998x: always enable EDID read IRQ

There is no need to enable/disable EDID read IRQ at each EDID block
read. This patch enables the IRQ at init time.

Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>