[coreboot] dead Kconfig variables in v3

[Carl-Daniel Hailfinger]

The following config variables are tested in the code, but don't exist
in Kconfig:
CONFIG_ADDR
CONFIG_AGP_PLUGIN_SUPPORT
CONFIG_BIG_ENDIAN
CONFIG_CARDBUS_PLUGIN_SUPPORT
CONFIG_CARTEST
CONFIG_CMD
CONFIG_HYPERTRANSPORT_PLUGIN_SUPPORT
CONFIG_MMCONF_SUPPORT
CONFIG_PCIE_PLUGIN_SUPPORT
CONFIG_PCIX_PLUGIN_SUPPORT
CONFIG_ROMSIZE
CONFIG_STAGE0
CONFIG_VIDEO_MB
CONFIG_XIP_ROM_BASE
CONFIG_XIP_ROM_SIZE

Should we just kill the code they are protecting or should we introcude
Kconfig variables for them?

Regards,
Carl-Daniel