kirkstone: Converted to new syntax

Since Yocto Honister, a new syntax for the OVERRIDES is used.
Converted the syntax in all recipes, configs, etc. to the new syntax.
Also the MACHINE_OVERRIDES from the meta-freescale layer have changed.
For more info regarding the NXP changes see
https://git.yoctoproject.org/meta-freescale/tree/scripts/convert-bsp-specific-overrides.