ARM: dts: stm32: Fix audio routing on STM32MP15xx DHCOM PDK2

The audio routing flow is not correct, the flow should be from source
(second element in the pair) to sink (first element in the pair). The
flow now is from "HP_OUT" to "Playback", where "Playback" is source
and "HP_OUT" is sink, i.e. the direction is swapped and there is no
direct link between the two either.

Fill in the correct routing, where "HP_OUT" supplies the "Headphone Jack",
"Line In Jack" supplies "LINE_IN" input, "Microphone Jack" supplies "MIC_IN"
input and "Mic Bias" supplies "Microphone Jack".

Fixes: 34e0c784 ("ARM: dts: stm32: Add DH Electronics DHCOM STM32MP1 SoM and PDK2 board")
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>