x86/mm: Redefine some of page table helpers as macros

This is preparation for the next patch, which would change
pgtable_l5_enabled to be cpu_feature_enabled(X86_FEATURE_LA57).

The change makes few helpers in paravirt.h dependent on
cpu_feature_enabled() definition from cpufeature.h.
And cpufeature.h is dependent on paravirt.h.

Let's re-define some of helpers as macros to break this dependency loop.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180216114948.68868-3-kirill.shutemov@linux.intel.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>