uboot-phytec

SPL: P2020RDB: fix the problem booting from spi flash

There was no enough stack in SPL, so the buffer needed in SPL is to malloc
from memory pool and to repalce the temporary variable.

Signed-off-by: Ying Zhang <b40530@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>