kernelscripts: Migrate kernel build parameters to build scripts

Currently, the kernel make rules and build definitions live
in the target specific AndroidBoard makefile. However,
these parameters are used solely to build the kernel, so
lets migrate them to the kernel build scripts so that this
information can be isolated to the kernel build environment.

Change-Id: I4e2e36e5b5a0d30a915443c0cdcdc05e8e49e2bc
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>