mb/siemens/mc_apl6: Enable eMMC

Enable eMMC with HS200 mode for mc_apl6 mainboard.

TEST: Linux booted and checked with 'lspci'.

Change-Id: Ib760a1a26a92047e8916979ffb5001bcff0a6e45
Signed-off-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45898
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-by: Maxim Polyakov <max.senia.poliak@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/mainboard/siemens/mc_apl1/variants/mc_apl6/devicetree.cb b/src/mainboard/siemens/mc_apl1/variants/mc_apl6/devicetree.cb
index 4aa8bc9..024f2c5 100644
--- a/src/mainboard/siemens/mc_apl1/variants/mc_apl6/devicetree.cb
+++ b/src/mainboard/siemens/mc_apl1/variants/mc_apl6/devicetree.cb
@@ -14,6 +14,9 @@
 	register "pcie_rp_clkreq_pin[4]" = "CLKREQ_DISABLED"
 	register "pcie_rp_clkreq_pin[5]" = "CLKREQ_DISABLED"
 
+	# 0:HS400(Default), 1:HS200, 2:DDR50
+	register "emmc_host_max_speed" = "1"
+
 	# Enable Vtd feature
 	register "enable_vtd" = "1"
 
@@ -70,7 +73,7 @@
 		device pci 19.2 off end	# - SPI 2
 		device pci 1a.0 off end	# - PWM
 		device pci 1b.0 on  end	# - SDCARD
-		device pci 1c.0 off end	# - eMMC
+		device pci 1c.0 on  end	# - eMMC
 		device pci 1d.0 off end	# - UFS
 		device pci 1e.0 off end	# - SDIO
 		device pci 1f.0 on	# - LPC