powerpc: Add PPC_NOP_INSTR, a hash define for the preferred nop instruction

A bunch of code has hard-coded the value for a "nop" instruction, it
would be nice to have a #define for it.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index 2664854..e0debcc 100644
--- a/arch/powerpc/kernel/crash_dump.c
+++ b/arch/powerpc/kernel/crash_dump.c
@@ -44,7 +44,7 @@
 	 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
 	 * two instructions it doesn't require any registers.
 	 */
-	patch_instruction(p, 0x60000000); /* nop */
+	patch_instruction(p, PPC_NOP_INSTR);
 	patch_branch(++p, addr + PHYSICAL_START, 0);
 }