1. able to set neon flags to sama5d2 & sama5d4 subtargets.
2. fix the make clean which removes all the subtargets in bin folder.
3. able to configure kernel specific to subtarget.
4. able to set vfpu4 flags to samad3 subtargets.
- using the ARMv7 instruction set.
+ using the ARMv7 instruction set.