ARM: use an easier way to create the empty built-in.o
We do not have to build an unneeded file to create the built-in.o.
Just add a dummy string to "obj-".
(dummy.c does not need to exist.)
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>