broadwell: Move some MRC/refcode settings to devicetree

There's no generic way to tell whether a mainboard has an EC or not.
Making Kconfig symbols for these options seems overkill, too. So, just
put them on the devicetree. Also, drop unnecessary assignments when the
board's current value is zero, as the struct defaults to zero already.

Change-Id: I8d3b352333bea7ea6f7b0f96d73e6c2d7d1a2cfb
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55809
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>

src/mainboard/google/jecht/devicetree.cb

@@ -9,6 +9,8 @@ chip soc/intel/broadwell
 	# Enable HDMI Hotplug with 6ms pulse
 	register "gpu_dp_b_hotplug" = "0x06"
 
+	register "dq_pins_interleaved" = "true"
+
 	device cpu_cluster 0 on
 		chip cpu/intel/haswell
 			device lapic 0 on end