arm: socfpga: gen5: combine some init code for SPL and U-Boot

Some of the code for low level system initialization in SPL's
board_init_f() and U-Boot's arch_early_init_r() is the same,
so let's combine it into a single function called from both.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>

arch/arm/mach-socfpga/include/mach/misc.h

@@ -27,6 +27,10 @@ unsigned int shared_uart_com_port(const void *blob);
 unsigned int uart_com_port(const void *blob);
 #endif
 
+#ifdef CONFIG_TARGET_SOCFPGA_GEN5
+void socfpga_sdram_remap_zero(void);
+#endif
+
 void do_bridge_reset(int enable);
 
 #endif /* _MISC_H_ */