ppc: xilinx_ppc440_generic: Remove uncalled functions

board_pre_init was not called because CONFIG_BOARD_EARLY_INIT_F was not
set. Remove unused function.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Acked-by: Stefan Roese <sr@denx.de>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Michal Simek <michal.simek@xilinx.com>

board/xilinx/ppc440-generic/xilinx_ppc440_generic.c

@@ -10,11 +10,6 @@
 #include <common.h>
 #include <asm/processor.h>
 
-int board_pre_init(void)
-{
-	return 0;
-}
-
 int checkboard(void)
 {
 	puts("Xilinx PPC440 Generic Board\n");