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>

arch/powerpc/net/bpf_jit_comp64.c

@@ -13,6 +13,7 @@
  */
 #include <linux/moduleloader.h>
 #include <asm/cacheflush.h>
+#include <asm/asm-compat.h>
 #include <linux/netdevice.h>
 #include <linux/filter.h>
 #include <linux/if_vlan.h>