intel: Add function to check fpga readiness

Create a function to check for fpga readiness, and move the checking out
of bridge enable function.

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I3f473ffeffa9ce181a48977560c8bda19c6123c0
diff --git a/plat/intel/soc/stratix10/bl2_plat_setup.c b/plat/intel/soc/stratix10/bl2_plat_setup.c
index 5eb7969..7d183db 100644
--- a/plat/intel/soc/stratix10/bl2_plat_setup.c
+++ b/plat/intel/soc/stratix10/bl2_plat_setup.c
@@ -73,7 +73,9 @@
 	socfpga_delay_timer_init();
 	init_hard_memory_controller();
 	mailbox_init();
-	socfpga_bridges_enable();
+
+	if (!intel_mailbox_is_fpga_not_ready())
+		socfpga_bridges_enable();
 }