mb/google/corsola: Add support for VIO18 in regulator.c

Add regulator VIO18 support to supply power for STA_HIMAX83102_J02 panel.

BUG=b:272425116
TEST=test firmware display pass for STA_HIMAX83102_J02 on Starmie.

Change-Id: Ie1dd9226b0c4f05f9c9ce6633b7384aa5eb4c978
Signed-off-by: Cong Yang <yangcong5@huaqin.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/74342
Reviewed-by: Yidi Lin <yidilin@google.com>
Reviewed-by: Ruihai Zhou <zhouruihai@huaqin.corp-partner.google.com>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/corsola/regulator.c

@@ -28,6 +28,8 @@ static int get_mt6366_regulator_id(enum mtk_regulator regulator)
 		return MT6366_VRF12;
 	case MTK_REGULATOR_VCN33:
 		return MT6366_VCN33;
+	case MTK_REGULATOR_VIO18:
+		return MT6366_VIO18;
 	default:
 		return MTK_REGULATOR_INVALID;
 	}