[POWERPC] Move inline asm eieio to using eieio inline function

Use the eieio function so we can redefine what eieio does rather
than direct inline asm.  This is part code clean up and partially
because not all PPCs have eieio (book-e has mbar that maps to eieio).

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/mm/hash_native_64.c

@@ -163,7 +163,7 @@ static long native_hpte_insert(unsigned long hpte_group, unsigned long va,
 
 	hptep->r = hpte_r;
 	/* Guarantee the second dword is visible before the valid bit */
-	__asm__ __volatile__ ("eieio" : : : "memory");
+	eieio();
 	/*
 	 * Now set the first dword including the valid bit
 	 * NOTE: this also unlocks the hpte