linux-wandboard

edm framework : change initcall and introduce baseboard and expansion control

change edm initcall to arch_initcall_sync, same as baseboards and expansions.
object file - edm.o should be linked prior than object files of baseboards and expansions.

allow initialization of baseboards and expansions can be controlled by
two argument "baseboard=" and "expansion=" in cmdline.

for now, cmdline is parsed by board files, should be modified to be parsed by edm.c
in the future.

Signed-off-by: Edward Lin <edward.lin@technexion.com>