powerpc: move ASM_CONST and stringify_in_c() into asm-const.h

This patch moves ASM_CONST() and stringify_in_c() into
dedicated asm-const.h, then cleans all related inclusions.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: asm-compat.h should include asm-const.h]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h
index f67b3f6..de13168 100644
--- a/arch/powerpc/include/asm/barrier.h
+++ b/arch/powerpc/include/asm/barrier.h
@@ -5,6 +5,8 @@
 #ifndef _ASM_POWERPC_BARRIER_H
 #define _ASM_POWERPC_BARRIER_H
 
+#include <asm/asm-const.h>
+
 /*
  * Memory barrier.
  * The sync instruction guarantees that all memory accesses initiated