Factor out a few commonly duplicated functions from northbridge.c.

Factor out a few commonly duplicated functions from northbridge.c.

The following functions are moved to devices/device_util.c:

 - ram_resource()

 - tolm_test()

 - find_pci_tolm()

There are only two tolm_test() / find_pci_tolm() which differ from the
defaults, one of them can easily be eliminated in a follow-up patch,
maybe even both, but for now keep it simple and only eliminate the majority.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Peter Stuge <peter@stuge.se>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5937 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1