scripts : add checkpatch.pl for k-hypervisor coding style

Add a modified version of the Linux kernel checkpatch.pl(version 0.31)
script. The k-hypervisor coding style is largely the same as the kernel,
except using spaces instead of tabs for indenting.

usage>
    scripts/checkpatch.pl --file <file_name>

reference : http://review.whamcloud.com/#/c/1167/