powerpc: Fix CONFIG_RELOCATABLE=y CONFIG_CRASH_DUMP=n build

If we build a kernel with CONFIG_RELOCATABLE=y CONFIG_CRASH_DUMP=n,
the kernel fails when we run at a non zero offset. It turns out
we were incorrectly wrapping some of the relocatable kernel code
with CONFIG_CRASH_DUMP.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Cc: <stable@kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/head_64.S

@@ -422,7 +422,7 @@ _STATIC(__after_prom_start)
 	tovirt(r6,r6)			/* on booke, we already run at PAGE_OFFSET */
 #endif
 
-#ifdef CONFIG_CRASH_DUMP
+#ifdef CONFIG_RELOCATABLE
 /*
  * Check if the kernel has to be running as relocatable kernel based on the
  * variable __run_at_load, if it is set the kernel is treated as relocatable