AST2500: Add loop device support in defconfig

Without this kernel is unable to mount loop device, and cause the init
script failing to copy rofs into ram in legacy code update.

Resolves openbmc/openbmc#3064.

Tested: Successfully run legacy code update on Romulus.

Change-Id: I22cdff51ac24a8ca00e1ed2b5d1d06d827b9eb74
Signed-off-by: Lei YU <mine260309@gmail.com>
1 file changed