ppc: xilinx_ppc405_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/ppc405-generic/xilinx_ppc405_generic.c

@@ -15,11 +15,6 @@ ulong get_PCI_freq(void)
 	return 0;
 }
 
-int board_pre_init(void)
-{
-	return 0;
-}
-
 int checkboard(void)
 {
 	puts("Xilinx PPC405 Generic Board\n");