ARM: zynq: Add uEnv.txt support

preboot macro load the uEnv.txt from mmc 0 when bootmode is mmc. uenvcmd is
executed after load of uEnv.txt if it is defined in the uEnv.txt env text
file.

The default importbootenv macro reads the uEnv.txt from mmc.

Additional to this, usb_loadbootenv is added to support loading uEnv.txt
from usb dev 0.

Signed-off-by: Jason Wu <jason.wu.misc@gmail.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
1 file changed