[coreboot] Jenkins: Use a config file with more stuff enabled

[Paul Menzel]

Dear coreboot folks,

for example the patch adding the spkmodem console [1] is currently not
build tested as it is disabled by default.

Could we put a `.config.jenkins` file into the repository where more
stuff is enabled so it gets tested too.

Patrick said something about Linux’ `allyesconfig` option. But this
would require getting latest Kconfig into coreboot I think. So using the
approach with just adding a separate config file for Jenkins might be
easier?

Thanks,

Paul

[1] http://review.coreboot.org/#/c/2987/