scripts: remove variant defconfig support

Change-Id: I26471f434010c343fae9104145c01f3f9052dac7
Conform defconfig to CM's unified variant setup and remove
unused defconfigs

Change-Id: Ic73d05fbebc72913f9c13fe9fc1b77a7f9df7681

Conflicts:
	arch/arm/configs/cyanogen_jf_defconfig