ARM: dts: imx: Synchronize iMX6QDL DHCOM PDK2 DTs with Linux 5.15.12

ARM: dts: imx: Synchronize iMX6QDL DHCOM PDK2 DTs with Linux 5.15.12

Synchronize DH DHCOM DTs with Linux commit 25960cafa06e ("Linux 5.15.12").
There is no functional change to the resulting DTs. The imx6qdl-dhcom-pdk2.dtsi
had to be adjusted with additional headers, gpio.h, pwm.h, input.h, else
the DT cannot be compiled, the same change is likely necessary in Linux.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Cc: Stefano Babic <sbabic@denx.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>