arm: socfpga: stratix10: Add mailbox support for Stratix10 SoC

Add mailbox support for Stratix SoC

Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>
Signed-off-by: Chin Liang See <chin.liang.see@intel.com>
Reviewed-by: Marek Vasut <marex@denx.de>
diff --git a/arch/arm/mach-socfpga/Makefile b/arch/arm/mach-socfpga/Makefile
index c74fec2..5c22cc2 100644
--- a/arch/arm/mach-socfpga/Makefile
+++ b/arch/arm/mach-socfpga/Makefile
@@ -30,6 +30,7 @@
 
 ifdef CONFIG_TARGET_SOCFPGA_STRATIX10
 obj-y	+= clock_manager_s10.o
+obj-y	+= mailbox_s10.o
 obj-y	+= misc_s10.o
 obj-y	+= reset_manager_s10.o
 obj-y	+= system_manager_s10.o