arm: socfpga: Add secure register access helper functions for SoC 64bits

These secure register access functions allow U-Boot proper running
at EL2 (non-secure) to access System Manager's secure registers
by calling the ATF's PSCI runtime services (EL3/secure).

Signed-off-by: Siew Chin Lim <elly.siew.chin.lim@intel.com>
Reviewed-by: Ley Foon Tan <ley.foon.tan@intel.com>
diff --git a/arch/arm/mach-socfpga/Makefile b/arch/arm/mach-socfpga/Makefile
index 0b05283..82b681d 100644
--- a/arch/arm/mach-socfpga/Makefile
+++ b/arch/arm/mach-socfpga/Makefile
@@ -73,6 +73,7 @@
 obj-y	+= spl_agilex.o
 endif
 else
+obj-$(CONFIG_SPL_ATF) += secure_reg_helper.o
 obj-$(CONFIG_SPL_ATF) += smc_api.o
 endif