arm: socfpga: Move Stratix10 and Agilex system manager common code

Move Stratix10 and Agilex system manager common code to
system_manager_soc64.h. Changed macros to use SYSMGR_SOC64_*.

Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>
Reviewed-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
diff --git a/arch/arm/mach-socfpga/mailbox_s10.c b/arch/arm/mach-socfpga/mailbox_s10.c
index 3b9a2ec..3254bc1 100644
--- a/arch/arm/mach-socfpga/mailbox_s10.c
+++ b/arch/arm/mach-socfpga/mailbox_s10.c
@@ -316,7 +316,7 @@
 	/* We are getting QSPI ref clock and set into sysmgr boot register */
 	printf("QSPI: Reference clock at %d Hz\n", resp_buf[0]);
 	writel(resp_buf[0],
-	       socfpga_get_sysmgr_addr() + SYSMGR_S10_BOOT_SCRATCH_COLD0);
+	       socfpga_get_sysmgr_addr() + SYSMGR_SOC64_BOOT_SCRATCH_COLD0);
 
 	return 0;