ccache and scan-build actually work together, so remove the

ccache and scan-build actually work together, so remove the
restriction that tells Kconfig not to allow that setup.
It's not particularily useful, as scan-build totally dominates
the gcc runtime, but well..

Signed-off-by: Patrick Georgi <patrick.georgi@coresystems.de>
Acked-by: Patrick Georgi <patrick.georgi@coresystems.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5305 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1