arm: use the correct prototype for reset_cpu function

Align reset_cpu function with the next prototypes in
sysreset.h or in cpu_func.h to solve compilation issue:

  void reset_cpu(void);

This patch solves the prototype conflict when cpu_func.h is
included.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>

board/congatec/cgtqmx8/cgtqmx8.c

@@ -374,7 +374,7 @@ void detail_board_ddr_info(void)
 /*
  * Board specific reset that is system reset.
  */
-void reset_cpu(ulong addr)
+void reset_cpu(void)
 {
 	/* TODO */
 }