drm/i2c: tda998x: remove complexity from tda998x_audio_get_eld()

tda998x_audio_get_eld() is needlessly complex - the connector associated
with the encoder is always our own priv->connector.  Remove this
complexity, but ensure that there are no races when copying out the ELD.

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>