Add make_defconfig script

tools for save defconfig
$ ./make_defconfig.sh mako-perf_defconfig
it will update in arch/arm/configs

Change-Id: Ic4946b4ac020faf7026bde216b480994ff9a71a8
presto: defconfig: auto-generated

Generated with: ./make_defconfig.sh cyanogenmod_presto_defconfig

Change-Id: I6b66f1b0c85b3481b4fe50adf05f26a1dee3a01d