ARM: PSCI: export common PSCI function declarations for C code

Some common PSCI functions are written in assembly, but it should be
possible to use them from C code.

Add function declarations for C code to consume.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

arch/arm/include/asm/psci.h

@@ -48,6 +48,13 @@
 #define ARM_PSCI_0_2_FN_SYSTEM_RESET		ARM_PSCI_0_2_FN(9)
 
 #ifndef __ASSEMBLY__
+#include <asm/types.h>
+
+void psci_cpu_entry(void);
+u32 psci_get_cpu_id(void);
+u32 psci_get_cpu_stack_top(int cpu);
+void psci_cpu_off_common(void);
+
 int psci_update_dt(void *fdt);
 void psci_board_init(void);
 #endif /* ! __ASSEMBLY__ */