intel: mailbox: Ensure time out duration is predictive

For each count down of time out counter, wait for number of
miliseconds to ensure the time out duration is predictive.

Signed-off-by: Chee Hong Ang <chee.hong.ang@intel.com>
Change-Id: I0e92dd1ef1da0ef504ec86472cf0d3c88528930b
diff --git a/plat/intel/soc/agilex/bl31_plat_setup.c b/plat/intel/soc/agilex/bl31_plat_setup.c
index 436538b..168236b 100644
--- a/plat/intel/soc/agilex/bl31_plat_setup.c
+++ b/plat/intel/soc/agilex/bl31_plat_setup.c
@@ -101,6 +101,8 @@
  ******************************************************************************/
 void bl31_platform_setup(void)
 {
+	socfpga_delay_timer_init();
+
 	/* Initialize the gic cpu and distributor interfaces */
 	gicv2_driver_init(&plat_gicv2_gic_data);
 	gicv2_distif_init();