drm/i2c: tda998x: fix bad checksum of the HDMI AVI infoframe

The commit 8c7a075d
"drm/i2c: tda998x: use drm_hdmi_avi_infoframe_from_display_mode()"
also uses hdmi_avi_infoframe_pack() to create the AVI infoframe.
This function sets the checksum of the frame and this breaks
the second calculation of the checksum done in tda998x_write_if().

Fixes: 8c7a075d ("drm/i2c: tda998x: use drm_hdmi_avi_infoframe_from_display_mode()")
Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/gpu/drm/i2c/tda998x_drv.c

@@ -582,8 +582,6 @@ static void
 tda998x_write_if(struct tda998x_priv *priv, uint8_t bit, uint16_t addr,
 		 uint8_t *buf, size_t size)
 {
-	buf[PB(0)] = tda998x_cksum(buf, size);
-
 	reg_clear(priv, REG_DIP_IF_FLAGS, bit);
 	reg_write_range(priv, addr, buf, size);
 	reg_set(priv, REG_DIP_IF_FLAGS, bit);
@@ -603,6 +601,8 @@ tda998x_write_aif(struct tda998x_priv *priv, struct tda998x_encoder_params *p)
 	buf[PB(4)] = p->audio_frame[4];
 	buf[PB(5)] = p->audio_frame[5] & 0xf8; /* DM_INH + LSV */
 
+	buf[PB(0)] = tda998x_cksum(buf, sizeof(buf));
+
 	tda998x_write_if(priv, DIP_IF_FLAGS_IF4, REG_IF4_HB0, buf,
 			 sizeof(buf));
 }