x86: move dwarf2 related macro to dwarf2.h

Impact: cleanup

Move recently introduced dwarf2 macros to dwarf2.h file.
It allow us to not duplicate them in assembly files.

Active usage of _cfi macros don't make assembly files
more obvious to understand but we already have a lot of
macros there which requires to search the definitions
of them *anyway*. But at least it make every cfi usage
one line shorter.

Also some code alignment is done.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>