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/page.h b/arch/powerpc/include/asm/page.h
index a9fbefa..f6a1265 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -16,7 +16,7 @@
 #else
 #include <asm/types.h>
 #endif
-#include <asm/asm-compat.h>
+#include <asm/asm-const.h>
 
 /*
  * On regular PPC32 page size is 4K (but we support 4K/16K/64K/256K pages