The debug environment which is stored in textfiles in the
scripts directory was reworked. Two usecase are now present
which can be executed simply from the default environment:
run develop: this configures the environment to setup the
             rootfs via nfs
run ramfs: this configures the environment to setup the
           rootfs in ram

Each architecture now has a "arch" variable which is used
to load the architecture specific debug scripts and to set
the rootpath for NFS.

Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com>
cc: Heiko Schocher <hs@denx.de>
cc: Wolfgang Denk <wd@denx.de>