[el1p2c] Replaced the declaration Scalar withStabilization_ by bool withStabilization_ to get rid of the floating point comparison warning.

(reviewed by gruenich)

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@13651 2fb0f335-1f38-0410-981e-8018bf24f1b0