armv8: Add read_mpidr() function

This patch adds the read_mpidr() function which returns the
MPIDR_EL1 register value

Signed-off-by: Sergey Temerkhanov <s.temerkhanov@gmail.com>
Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>

Reviewed-by: Simon Glass <sjg@chromium.org>

arch/arm/include/asm/system.h

@@ -72,6 +72,17 @@ static inline void set_sctlr(unsigned int val)
 	asm volatile("isb");
 }
 
+static inline unsigned long read_mpidr(void)
+{
+	unsigned long val;
+
+	asm volatile("mrs %0, mpidr_el1" : "=r" (val));
+
+	return val;
+}
+
+#define BSP_COREID	0
+
 void __asm_flush_dcache_all(void);
 void __asm_invalidate_dcache_all(void);
 void __asm_flush_dcache_range(u64 start, u64 end);