mb/google/rauru: Fully calibrate DRAM

Initialize and calibrate DRAM in romstage.

DRAM full calibration logs:
dram_init: dram init end (result: 0)
DRAM-K:
Fast calibration passed in 1119 msecs

TEST=Full calibration pass.
BUG=b:317009620

Change-Id: Ibb18675caa11a828d27860eeab48c49acf6b938d
Signed-off-by: Jarried Lin <jarried.lin@mediatek.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/85120
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yidi Lin <yidilin@google.com>

src/mainboard/google/rauru/romstage.c

@@ -1,12 +1,14 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
 #include <arch/stages.h>
+#include <soc/emi.h>
 #include <soc/irq2axi.h>
 #include <soc/pcie.h>
 
 void platform_romstage_main(void)
 {
 	irq2axi_disable();
+	mtk_dram_init();
 
 	if (CONFIG(PCI))
 		mtk_pcie_deassert_perst();