drm/i2c: tda998x: move drm_i2c_encoder_destroy call

Currently tda998x_encoder_destroy() calls cec_write() and reg_clear(),
as part of the release procedure. Such calls need to access the I2C bus
and therefore, we need to call them before drm_i2c_encoder_destroy()
which unregisters the I2C device.

This commit moves the latter so it's done afterwards.

Signed-off-by: Guido Martínez <guido@vanguardiasur.com.ar>
Signed-off-by: Ezequiel García <ezequiel@vanguardiasur.com.ar>
Cc: <stable@vger.kernel.org> #v3.9+
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>