snow/pit: include chromeos.c in romstage

When CONFIG_CHROMEOS is enabled, both systems currently fail to build
romstage due to undefined symbols.

Change-Id: I0edcb141b9a79fad6b1a629bf77cae656c3d6319
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6873
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/mainboard/google/pit/Makefile.inc

@@ -22,6 +22,7 @@ bootblock-y += wakeup.c
 romstage-y += memory.c
 romstage-y += romstage.c
 romstage-y += wakeup.c
+romstage-y += chromeos.c
 
 ramstage-y += mainboard.c
 ramstage-y += chromeos.c

src/mainboard/google/snow/Makefile.inc

@@ -22,6 +22,7 @@ bootblock-y += wakeup.c
 romstage-y += memory.c
 romstage-y += romstage.c
 romstage-y += wakeup.c
+romstage-y += chromeos.c
 
 ramstage-y += mainboard.c
 ramstage-y += chromeos.c