ARM: socfpga: add reset for the Arria 10 platform

Since the Arria10's reset register offset is different from the Cyclone/Arria 5,
it's best to add a new DT_MACHINE_START() for the Arria10.

Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>
---
v2: use altera_a10_dt_match for the A10 machine desc
diff --git a/arch/arm/mach-socfpga/core.h b/arch/arm/mach-socfpga/core.h
index 7259c37..5bc6ea8 100644
--- a/arch/arm/mach-socfpga/core.h
+++ b/arch/arm/mach-socfpga/core.h
@@ -25,6 +25,7 @@
 #define SOCFPGA_RSTMGR_MODPERRST	0x14
 #define SOCFPGA_RSTMGR_BRGMODRST	0x1c
 
+#define SOCFPGA_A10_RSTMGR_CTRL		0xC
 #define SOCFPGA_A10_RSTMGR_MODMPURST	0x20
 
 /* System Manager bits */