Minor cleanups to inline sources

Some of the assembly has been consolidated inline as well as some new additions.
Added extra assembly functions

With the functions listed at http://wiki.osdev.org/Inline_Assembly/Examples#PGFLUSHTLB, the
util.h header now has a few more functions. This won't be their final place, but will be
distributed into different parts of the kernel as those areas are complete. See CPUID for
an example - it's in its own module.