xilinx: Setup bootm variables

On system with PL DDR which is placed before PS DDR in DT
env_get_bootm_size() and env_get_bootm_low() without specifying bootm_low
and bootm_size variables are taking by default gd->bd->bi_dram[0].start and
gd->bd->bi_dram[0].size. As you see 0 means bank 0 which doesn't need to be
PS ddr and even can be memory above 39bit VA which is what U-Boot supports
now.
That's why setup bootm variables based on ram_base/ram_size setting to make
sure that boot images are placed to the same location as U-Boot is placed.
This location should be by default location where OS can boot from.
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>

board/xilinx/common/board.c

@@ -86,5 +86,8 @@ int board_late_init_xilinx(void)
 	initrd_hi = round_down(initrd_hi, SZ_16M);
 	env_set_addr("initrd_high", (void *)initrd_hi);
 
+	env_set_addr("bootm_low", (void *)gd->ram_base);
+	env_set_addr("bootm_size", (void *)gd->ram_size);
+
 	return 0;
 }