mb/siemens/mc_ehl2: Adjust PCIe clock source settings in devicetree
With latest hardware revision all clock outputs will be used on this
mainboard. For this reason set all clock source mappings to
'PCIE_CLK_FREE' to have a free running clock.
Change-Id: Ic3f6fb4e24128742ed72dade7a4555c39fb722ae
Signed-off-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59259
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>