microblaze: Fix board_init calling sequence

board_init() is in final elf file but it is not called at all.
Use board_init_late() instead and call gpio_init() from it.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/include/configs/microblaze-generic.h b/include/configs/microblaze-generic.h
index 3cbec65..97a0d86 100644
--- a/include/configs/microblaze-generic.h
+++ b/include/configs/microblaze-generic.h
@@ -45,6 +45,7 @@
 # define CONFIG_XILINX_GPIO
 # define CONFIG_SYS_GPIO_0_ADDR		XILINX_GPIO_BASEADDR
 #endif
+#define CONFIG_BOARD_LATE_INIT
 
 /* interrupt controller */
 #ifdef XILINX_INTC_BASEADDR