uboot-phytec

env_nand.c: print error message and fail gracefully

env_nand.c would crash silently if a malloc() for the environment
buffers failed; make it print an error message and fail gracefully,
i. e. use the default environment then.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-by: John Rigby <jcrigby@gmail.com>