drm/bridge: dw-hdmi-qp: fix multi-channel audio output

drm/bridge: dw-hdmi-qp: fix multi-channel audio output

Channel Allocation (PB4) and Level Shift Information (PB5) are
configured with values from PB1 and PB2 due to the wrong offset
being used. This results in missing audio channels or incorrect
speaker placement when playing multi-channel audio.

Use the correct offset to fix multi-channel audio output.

Fixes: fd0141d1a8a2 ("drm/bridge: synopsys: Add audio support for dw-hdmi-qp")
Reported-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Reviewed-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Link: https://patch.msgid.link/20260228112822.4056354-1-christianshewitt@gmail.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>