amd/lx: Move configuration from source to Kconfig

LX has two values that are usually automatically derived but can
be overridden, that were so far defined in each board's romstage.

These values, along with the toggle to enable override are now
part of LX's Kconfig. For boards that gave values but requested
autogeneration, the values are removed.

Further improvements: Figure out the various fields in PLLMSRlo
and make them sensible Kconfig options (instead of the hex value
it is now)

Change-Id: I8a17c89e4a3cb1b52aaceef645955ab7817b482d
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/1227
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
26 files changed