build system: remove ROMSTAGE_ELF variable

No need to keep that just because x86 has one
extra linking step.

Change-Id: Iffdbf64e0613f89070ed0dfb009379f5ca0bd3c1
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: http://review.coreboot.org/7611
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
2 files changed