ChromeOS boards: Use explicit include of chromeos.c

Change-Id: I7b3d044fad1d6973910e9bef347478a45c149a4f
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/5640
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/vendorcode/google/chromeos/Makefile.inc

@@ -27,10 +27,6 @@ romstage-y += fmap.c
 ramstage-y += fmap.c
 ramstage-$(CONFIG_CHROMEOS_RAMOOPS) += ramoops.c
 smm-y += fmap.c
-ifneq ($(wildcard src/mainboard/$(MAINBOARDDIR)/chromeos.c),)
-ramstage-srcs += src/mainboard/$(MAINBOARDDIR)/chromeos.c
-romstage-srcs += src/mainboard/$(MAINBOARDDIR)/chromeos.c
-endif
 
 ifeq ($(MOCK_TPM),1)
 CFLAGS_common += -DMOCK_TPM=1