powerpc/kdump: crash_dump.c needs to include io.h

For __ioremap().
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/crash_dump.c

@@ -13,6 +13,7 @@
 
 #include <linux/crash_dump.h>
 #include <linux/bootmem.h>
+#include <linux/io.h>
 #include <linux/memblock.h>
 #include <asm/code-patching.h>
 #include <asm/kdump.h>