drm/i2c: tda998x: code cleanup

This patch:
- replaces ARRAY_SIZE() by sizeof() when a number of bytes is needed,
- adds a linefeed in an error message and
- removes an useless variable setting.

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>