drm/i2c: tda998x: correct function name in comments

Correct two references to tda998x_connector_get_modes() which were
incorrectly referring to tda998x_encoder_get_modes().

Tested-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Jon Medhurst <tixy@linaro.org>
Acked-by: Jon Medhurst <tixy@linaro.org>
Tested-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>