Fix build with CMOS support on various platforms

When bringing in nvramtool as build_opt_tbl replacement,
various platforms where left in the cold that don't
provide direct IO support from userland (or at least not
in a way we support).

Build nvramtool without CMOS support when done as part of
a coreboot build. We don't need to touch CMOS in this case.

Change-Id: Icc88d1d32f10384867a5d44b065f9aa119bb0d50
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/983
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marcj303@gmail.com>

util/nvramtool/Makefile.inc

@@ -37,7 +37,7 @@ nvramtoolobj :=
 nvramtoolobj += cli/nvramtool.o cli/opts.o
 nvramtoolobj += cmos_lowlevel.o cmos_ops.o common.o compute_ip_checksum.o
 nvramtoolobj += hexdump.o input_file.o layout.o accessors/layout-common.o accessors/layout-text.o accessors/layout-bin.o lbtable.o
-nvramtoolobj += reg_expr.o cbfs.o accessors/cmos-hw-unix.o accessors/cmos-mem.o
+nvramtoolobj += reg_expr.o cbfs.o accessors/cmos-mem.o
 
 $(objutil)/nvramtool $(objutil)/nvramtool/accessors $(objutil)/nvramtool/cli:
 	mkdir -p $@