mb/google/geralt: Increase VM18 LDO voltage to 1.9V for Ciri

The current panel voltage measured at mainboard side is 1.79V and the
voltage at panel side is 1.74V. Since the panel requires 1.8V or more,
increase the circuit voltage to 1.9V to meet the panel requirement.
After adjustment mainboard side voltage is 1.89V and panel side is
1.84V.

BUG=b:322080023
TEST=Check ciri vm18 ldo voltage
BRANCH=None

Change-Id: I6d6193d45409f53c0b656890c44ddaef253c5e01
Signed-off-by: Cong Yang <yangcong5@huaqin.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80198
Reviewed-by: Ruihai Zhou <zhouruihai@huaqin.corp-partner.google.com>
Reviewed-by: Yidi Lin <yidilin@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/geralt/panel_ciri.c

@@ -2,6 +2,7 @@
 
 #include <console/console.h>
 #include <soc/i2c.h>
+#include <soc/regulator.h>
 
 #include "gpio.h"
 #include "panel.h"
@@ -23,6 +24,7 @@ static void power_on_mipi_himax_83102j(void)
 		.settings = reg_settings,
 		.setting_counts = ARRAY_SIZE(reg_settings),
 	};
+	mainboard_set_regulator_voltage(MTK_REGULATOR_VDD18, 1900000);
 	power_on_mipi_panel(&cfg);
 }
 

src/mainboard/google/geralt/regulator.c

@@ -38,6 +38,8 @@ void mainboard_set_regulator_voltage(enum mtk_regulator regulator, uint32_t volt
 
 	if (id == MT6359P_SIM1)
 		mt6359p_set_vsim1_voltage(voltage_uv);
+	else if (id == MT6359P_VM18)
+		mt6359p_set_vm18_voltage(voltage_uv);
 	else
 		mt6359p_buck_set_voltage(id, voltage_uv);
 }