[coreboot] [PATCH]Unify romstage.inc handling

[Patrick Georgi]

Hi,

attached patch moves all the copies of the romstage.inc rule to
src/arch/i386/Makefile.inc

For that to work, I had to:
- Add a CONFIG_ROMCC variable
- Set that variable on all ROMCC boards
- conditionally choose romcc or gcc rule based on that variable
- remove those two rules from all the boards' Makefiles
- switch a couple of boards to HAVE_OPTION_TABLE, as they actually have.

I also removed the duplication of rules with the sole difference of if
they depend on option_table.h or not.

Signed-off-by: Patrick Georgi