feat(plat/mediatek/mt8186): initialize delay_timer

Initialize delay_timer for delay functions.

TEST=build pass
BUG=b:202871018

Change-Id: Ib8f52d1c674537795cc478015c83cca0f872df60
diff --git a/plat/mediatek/mt8186/bl31_plat_setup.c b/plat/mediatek/mt8186/bl31_plat_setup.c
index 8359b9a..3734f91 100644
--- a/plat/mediatek/mt8186/bl31_plat_setup.c
+++ b/plat/mediatek/mt8186/bl31_plat_setup.c
@@ -11,6 +11,7 @@
 #include <common/bl_common.h>
 #include <common/debug.h>
 #include <common/desc_image_load.h>
+#include <drivers/generic_delay_timer.h>
 #include <drivers/ti/uart/uart_16550.h>
 #include <lib/coreboot.h>
 
@@ -82,6 +83,8 @@
 void bl31_platform_setup(void)
 {
 	mt_systimer_init();
+	generic_delay_timer_init();
+
 	emi_mpu_init();
 }