drm/bridge: adv7511_audio: Update Audio InfoFrame properly

drm/bridge: adv7511_audio: Update Audio InfoFrame properly

AUDIO_UPDATE bit (Bit 5 of MAIN register 0x4A) needs to be set to 1
while updating Audio InfoFrame information and then set to 0 when done.
Otherwise partially updated Audio InfoFrames could be sent out. Two
cases where this rule were not followed are fixed:
 - In adv7511_hdmi_hw_params() make sure AUDIO_UPDATE bit is updated
   before/after setting ADV7511_REG_AUDIO_INFOFRAME.
 - In audio_startup() use the correct register for clearing
   AUDIO_UPDATE bit.

The problem with corrupted audio infoframes were discovered by letting
a HDMI logic analyser check the output of ADV7535.

Note that this patchs replaces writing REG_GC(1) with
REG_INFOFRAME_UPDATE. Bit 5 of REG_GC(1) is positioned within field
GC_PP[3:0] and that field doesn't control audio infoframe and is read-
only. My conclusion therefore was that the author if this code meant to
clear bit 5 of REG_INFOFRAME_UPDATE from the very beginning.

Tested-by: Biju Das <biju.das.jz@bp.renesas.com>
Fixes: 53c515befe28 ("drm/bridge: adv7511: Add Audio support")
Signed-off-by: Stefan Ekenberg <stefan.ekenberg@axis.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241119-adv7511-audio-info-frame-v4-1-4ae68e76c89c@axis.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>